Enjoyable questions and problems

         Image created at my request by Microsoft Copilot  Sumi’s grandpa is very fussy about his food and drink. Recently he came to visit the family. At breakfast, he would not have coffee but asked for a glass of buttermilk. Sumi asked him if she should add salt to it. He said, “yes, but only 100 milligrams; no more!” Sumi scratched her head and remembered what she had learnt at the chemistry lab. There are a thousand milligrams in a gram. So, what grandpa wanted was one-tenth of a gram of salt. How do you measure it? If you try to weigh small of amounts of salt like that, the scale show zero as the weight! The kitchen scale weighed three grams accurately, but that is thirty times what grandpa wanted. So, Sumi took ninety grams of water in a glass and stirred 3-gram salt into it. It took a bit of time to dissolve completely. Then Sumi took three grams out of the water with salt and add added it to the buttermilk. Here Grandpa! You have a glass of butte...

  This is the self-portrait ChatGPT-5 painted for me Can you solve puzzles as well as ChatGPT-5? I gave it a problem, and he told me he would reword the problem as a puzzle to make it enjoyable. Here is his version of the problem: The Birthday Picnic Mystery   🎂🪁 One sunny afternoon, three siblings — A, the kite ‑ flyer, B, the whistler, and C, the master cake ‑ baker — were helping their parents pack for a picnic. While they worked, their mom smiled and said: I have just noticed something curious. Between the three of you, your total age is 20 years. C, you’re the oldest. You’re 4 years older than A, and 3 years older than B. Can you figure out exactly how old each of you is? The three looked at each other, grinned, and started scribbling in a notebook... 👉 Can you solve the problem before I tell you Chatty's answer on Monday, August 18? You can read the answer here any day after August 15. Srinivasan Ramani 

🌦️ The Bird That Brings the Rain: A Chat with AI Hi kids! Have you ever wanted to talk to a robot? I did—and guess what we talked about? A magical little bird that travels across the world to sing when the rain comes! Let me tell you how it went. AI means Artificial Intelligence.  🤖 Me: Hey AI, is there really a bird that flies from Africa to India just to sing? AI: Yes there is! It’s called the Pied Cuckoo , but some people call it the Rain Bird . It’s like a tiny traveler on a big adventure! 🚀 Me: But Africa is soooo far away! How can a small bird fly that far? AI: Great question! The Pied Cuckoo travels over 5,000 kilometers , crossing oceans and lands— with no pit stops! That’s like flying all the way from Mumbai to Tokyo without ever landing. It’s super hard! 🏋️ Me: Does it lose weight while flying? AI: Yes, it does. The bird only weighs about 65 to 75 grams —like a snack bar! During such a long flight, it gets really tired and can lo...

  People have believed in imaginary Unicorns. They are supposed to be beautiful creatures looking like horses. Unlike horses, they have a single, spiralling horn on their foreheads. Stories tell us that Unicorns are kind, gentle, and very wise. Their horns can cure people who are sick and purify water. Scientists have found buried bones of large creatures resembling horses with a single horn on their foreheads. These bones are 30,000 years old. Can you imagine going camping in a wildlife park and seeing a few unicorns eating grass and playing? Would you like to write a story about this experience? Srinivasan Ramani

Photo Credit: The Hindu, 26-Oct-2020   This Dussehra brought me a surprise. Every year Hindus worship the tools that give them a livelihood. Carpenters, Tailors, Plumbers and Electricians are some of those who decorate their tools with flowers. Car owners and drivers put garlands on their cars. However, many followed an avoidable practice. They used to smash Ash Gourds, also called white pumpkins, in front of their cars. I believe that did this to avoid the effect of “the evil eye”! Some of us consider that a waste of food. We prefer people to donate Ash Gourds to the needy and avoid creating a mess in parking areas inside buildings and streets. Even though dozens of cars are parked here, I did not see even one Ash Gourd smashed on the ground in our housing complex this year.  Another step forward I saw was the goodies we got for the festive season: dry fruit laddus with low sugar, baked nippats (traditionally crispy deep-fried rice crackers), and roasted peanuts without salt....

I see a big difference between well-educated people and others. Nowadays, much valuable information and knowledge comes through the Internet. However, anyone can write anything and send it to thousands of people at no cost. So much rubbish also comes along. Many of the stories that come to us over channels like WhatsApp, X, and email are untrue.  Read the following paragraphs and find the ones that do not appear true.  1) At just 10 years old, Tilly recognized the signs of an impending tsunami from a geography lesson she had two weeks earlier. She alerted her parents and other  beachgoers, leading to a beach evacuation just before the tsunami hit [1]. This saved a hundred lives. Newspapers carried the story and made her famous for her quick thinking.  [1]: en.wikipedia.org  2) A school in Boston, MA, held a unique competition for high ju mpers on Sunday, 9/29. Cars were parked side by side on a playground. Competitors had to choose how many cars they would jump ...

  Photo: Srinivasan Ramani  Young babies only understand what you are doing in front of them by imitating you. They are born with this ability, so even very young babies can do it. So, next time you play with a young baby, try this: Sit where the baby can see you. The effort may take several ten-minute sessions, so the baby should be comfortable and not distracted by movements nearby and sounds. Lifting your hands and the baby's hands once or twice in the beginning will show her where to look. You need patience. Sometimes, I spend an hour getting the baby to imitate me the first time. It is easier later; the baby treats this as a game. Sticking your tongue out and having the baby imitate that is another challenge to try another day. I once taught a baby girl to stick out her tongue. When her grandfather came home from work in the evening, the baby stuck out her tongue at him. She repeated this three or four times in fifteen minutes. The grandfather was worried, as he t...

If you see the marks students get in a subject in your class, you will find that the largest number of people get average marks, while the number of those getting higher than the average gradually reduces. Similarly, the number of those getting less than average also reduces as you move away from the average. When teachers make a graph of the marks earned by the class, they get something that looks like this:                                                                     Image Credit: Monika Wahi,  CC-BY-SA-4.0 ,                                      Image from Wikimedia Commons In this example, we assume that D is the average score 50%. Other points are: A          ...

Julius Caesar adopted a tricky method of sending messages to his generals through messengers. What if his enemies caught hold of the messenger and read the message? They will then know Caesar’s plans. Caesar’s trick was to change the letters in the message. For instance, he could write “D” instead of “A”, “E” instead of “B” and so on. Every letter would be replaced by another three places further down in the alphabetical order. What do you do with “Y”? What is three places beyond “Y”? The trick is to think of the letters being arranged in a ring so that “A” follows “Z” and “B” follows “A”. In this ring you can go three places from “Y” and find “B”. The letter three places ahead of “Z” will be “C”. To encipher a message, that is to make it secret, we first choose a key. I recommend that you choose a whole number between 1 and 6 as the key. Suppose you choose 3 as the key. Now replace every letter in “TEXT” by one which is 3 steps away along the ring. Do you get “WHAW”? You can send ...

Have you seen 2 3 , 3 5 and so on? Why are 3 and 5 sitting at a different level? It is just mathematicians’ shorthand: 2 3 is nothing but 2 x 2 x 2 =   8 3 5 means 3 x 3 x 3 x 3 x 3 = 243 We read 2 3 as 2 to the power 3, and 3 5 as 3 to the power five. What is 2 5 ?   Write it down. What is 2 3 x 2 5 ?   One surprising thing is that 2 3 x 2 5 = 2 8 = 256 Numbers sitting one level higher are called exponents. The exponent notation makes it very easy to write some big numbers. Try writing a million, billion and trillion! But with exponent notation, it is much easier to write them and remember them. Number In decimal notation In exponent notation Million 1,000,000 10 6 Billion 1,000,000,000 10 9 Trillion 1,000,000,000,000 10 12 Did you notice it? Million has six zero’s and is 10 6; billion has nine zero’s and is 10 9 ; trillion ...

  Nellie Bly. Photo Credit: Wikipedia Girls are as smart as boys. They may be smarter in some ways, like understanding people and in helping them. They may not be as good in fighting. In the old days, men controlled the world through hand-to-hand fighting and fighting with sticks and swords. However, times have changed. Women can now do most of the work men can. However, many countries do not allow girls to go to college or even high school. They do not allow women to work in offices. Such prejudice against women was there even in countries which are advanced countries now. Take the United States for example. A hundred and thirty-five years ago, a newspaper named the Pittsburgh Despatch carried an article with the title “What are girls good for?” It said that girls are good mainly for giving birth to children and for keeping house. A girl named Elizabeth, who was 21 years old at that time, did not agree with the article. She wrote a letter to the Editor of the paper arguing that ...

  PHOTO CREDIT: WIKIPEDIA    We had sweets to eat! You may wonder how the new year starts on April 14. Well! This is in Bengaluru and in Chennai, India. People of Tamil origin all over the world follow this practice. Several other states of India observe this day under different names. People from Kerala, the Punjab and Bengal are among those who celebrate New Year’s Day in April. This day used to be the day of the Spring Equinox when the Sun moves from the southern part of the sky to the northern part. For people living in the northern half of the world, this used to mark the beginning of Spring – warmer days and longer hours with sunlight. The Equinox occurs earlier nowadays. In 2023, it was on March 21. However, people stick to the practice of observing April 14 as the new year day. Srinivasan Ramani    

Photo credit: NASA and JPL. Image from Wikimedia Commons.  This image is licensed under the  Creative Commons   Attribution-Share Alike 3.0 Unported  license.  Some of the readers of this blog have been telling me that it is difficult to see Mercury. In Bengaluru, the Sun will rise at about 6:40 AM tomorrow. I have set the alarm to wake me up to see mercury at 6 AM. But it is not always easy for me to get up that early! I have found a good solution to the problem. Tomorrow, the Sun will set in the West, at about 6:30 PM, in Bengaluru. After seven PM, I will be able to see two bright planets in the west. I saw them today. The brighter one is Venus, and it will be lower in the sky than the other. The other one will be Jupiter. I am excited about these planets. More than four hundred years ago, in the year 1610, the Astronomer Galileo started observing these two planets with a home-made telescope. He saw that all of Venus was not uniformly lit. It has phases,...

  Image Credit: http://solarsystem.nasa.gov/planets/index.cfm . This is a montage of planetary images taken by spacecraft managed by the Jet Propulsion Laboratory in Pasadena, CA. Included are (from top to bottom) images of Mercury, Venus, Earth (and Moon), Mars, Jupiter, Saturn, Uranus and Neptune. Ask people you meet if they have seen the planet Mercury.  Most will say they have not seen it.  If they say they have seen it, ask them when they saw it and where.  Why is it so difficult to see? It is a planet close to the Sun. During part of the year, you see it rise on the eastern horizon. On some of these days you can see it about 45 minutes before sunrise. During another part of the year, it can be seen within 45 minutes of Sunset on Western horizon. You cannot see Mercury when the Sun is shining. The sunlight is much more powerful than the light from Mercury. It is dangerous to look at the Sun directly, because its rays can damage your eyes. Today, when I w...

  Cropped by Ramani. This file is licensed under the  Creative Commons   Attribution 3.0 Unported  license. Attribution:  Adeeb Atwan A fast motorbike went down our street one morning, making a big noise. Ten minutes later, my mom dropped her coffee mug. Can you say that the cause of mom dropping the coffee cup was the motorbike’s noise? Or was it a case of mere coincidence? This type of question was known long ago. An old Indian proverb talks about a crow and a palm tree. The crow came and sat on a palm tree and soon the tree fell down. Can we say that the crow’s sitting was the cause of the tree falling?    Or was it a case of mere coincidence? Srinivasan Ramani  

You know that drones are usually planes that fly without any pilots! They are controlled by a computer they carry.  Image Credit: NASA I think that very soon some drone will fly non-stop all around the equator, starting at some point on it and coming back to that point.  Suppose the drone flies at 100 miles per hour. How long will it take to fly a complete trip, flying over the equator?  You will have to know the distance involved. That depends on the size of the earth. Can you find out what is the distance the drone will have to fly? Then you can calculate how many hours it will take for the drone to fly this trip! Finally, you can convert the hours to days.  Talk to people who can help you with this calculation. Or perhaps, you can look up a book to find the distance involved. Ask the librarian in your school to show you an atlas. It will probably give you the answer. The librarian may help you find it.  Srinivasan Ramani 

  K452b Artist Impression Image Credit NASA and Wikimedia Commons Exoplanets are Planets outside our solar system. Over four thousand of them have been discovered. They orbit some star other than the Sun. Some are earth-like. They have temperatures suitable for living things. Some exoplanets even have an atmosphere. Some have hard surface at least in part so that life can live on it. Some other exoplanets are balls of gas! Scientists have not found any proof of living things on any of these exoplanets. Who knows, they may find proof of that in the coming years. The image above is not a photograph. It was an artist’s painting. NASA used it to tell news reporters in July 2015 about how its scientists found it. We don’t know much about it yet. It may be earth-like in some respects. It is in the constellation of Cygnus, the Swan.  Do you want to go there? Even if you travel at the speed of light, it will take approximately 1,800 years! We have no clue how we can travel that ...

       Photo: Irvin calicut, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons We had a partial solar eclipse on Tuesday, October 25, 2022. Today, Tuesday, Nov 8, 2022, we had a lunar eclipse. Is it a rare coincidence? Or is it that solar and lunar eclipses occur within 14 days of each other often? If so, why? Can you think of a reason? Can someone tell you? Srinivasan Ramani  

  We had a partial solar eclipse on Tuesday, November 25, 2022. It was a new moon day. We call it a partial solar eclipse when a part of the Sun is visible while the rest is covered. Is it true that solar eclipses occur only on new moons? Why don’t they occur every new moon? Discuss this with family members. Or ask a teacher. Can you watch a solar eclipse in future? Don’t do it unless you are with someone knowledgeable about it. Looking directly at the Sun is always dangerous. They will tell you how to observe an eclipse without hurting your eye.  The next solar eclipse would be on  April 8, 2024. It would be a total solar eclipse in some countries, including the USA. During a total solar eclipse, the whole Sun would be covered by a shadow.  Even that eclipse should NOT be observed by looking directly at the Sun.  Srinivasan Ramani

This is the story of our most recent common ancestor. She is called Mitochondrial Eve. She is different from the Eve mentioned in the bible. Scientists have found a method of extracting the substance named DNA from old bones. If they find two similar skeletons, by studying the DNA, they can say which is older. They can even say how much older. They can say which is an ape skeleton and which is a human skeleton. They can also say if the older skeleton is that of an ancestor of the other one. They can collect a sample of your DNA by merely rubbing a cotton bud on your inside-cheek. That will show them which part of the world your ancestors came from! Using these methods, scientists have identified a set of bones found buried in East Africa as being approximately 155,000 years old. From the skeleton’s shape and from the DNA, they know that it is the skeleton of a woman. The amazing discovery is that she is the ancestor of every human being on earth! We all have a common ancestor! The...