Hello guys my name is Yuya. I major in mathematics at my university. I’ll teach you something interesting with mathematics.

Maybe you can count to 10 using both your hands but I can count to 31 just using my right hand. If I used my both hands, I could count to 1023. Isn’t it incredible? I’ll show you how to count and how to use your hand.

Please spread your right hand. I’ll give each of your fingers a number like in the left picture.

 

 

 

 

Your thumb means 1, your index finger means 2, your middle finger means 4, your ring finger means 8, and your little finger means 16. Do you remember? Let’s count together.

First please put your thumb up. It means 1 and you can count 1. Please put your index finger up next. It means 2 and you can count 2. Please put your thumb and index finger up. Do you know it means 3 because you have 1 and 2. Let’s go to the next step. Of course if you just put up your middle finger, it means 4. However, how can we make 5? It’s easy because you just put up your thumb and middle finger. How about 6? It’s also easy because you just up your index finger and middle finger. Please keep going. Can you count 11? Please put your thumb, index finger and ring finger up. It’s 11 because you have 1, 2 and 8. So when your all fingers on your right hand one up, you are able to count 31 because you have 1, 2, 4, 8 and 16. If you add together it everything definitely becomes 31.

Interestingly, if you use both hands, you can count 1023 but it’s very hard. I put another picture here.

Try it yourself. Good luck.

Yuya Yamaguchi, Intermediate B