I read interesting book.It name is "You become not able to sleep becouse this is very very interesting mathematic a book!!(超面白くて眠れなくなる数学の本)
I use magic.For example,please prepare a calculator.
First.plese push 12345679 and multiply.
Second.Please push your favorite "A figure"
Thread.Please push 9 and multiply.
I will show your favorite a figure.
Why can I understand your favorite a figure?Becouse of I am magician!!
.....In fact,I explain a magic trick.
111111111×your favorite a figure=a lot of your favorite a figure.
There was written in this book.
If you like mathematic,please result it.