The number 9 is quite fascinating in mathematics. When you multiply any number by 9 and then add up the digits of the result, you’ll eventually end up with 9. Try it out! For example:
2 x 9 = 18 → 1 + 8 = 9
7 x 9 = 63 → 6 + 3 = 9
This property is known as the “digit sum” or “digital root” of a number.