Answer:
The number 10/7 is a rational number, which means it can be expressed as a fraction. Also, if we divide it would give a decimal infinite periodical number, which means it has a pattern on its decimal numbers.
On the other hand, the square root of 2 is irrational number, that means it can't be expressed as a fraction, because its decimal numbers don't have any pattern at all.
So, Mai's brother can see these type of numbers as crazy (irrational numbers) and sane (rational numbers).
At last, another important characteristic to shows that they aren't equal is that they don't have the exactly decimal numbers.
