Question

If 21y5 is a multiple of 9 where y is a digit what is value of y

Answer 1

Hello friend,
Heres your answer:

Property:
If a number should be divisible by nine, then the sum of the digits must be divisible by nine.

According to the property:
2 + 1 + y + 5 = Multiples of nine
=> 8 + y = 9 (suppose, because y must be 1 digit)
therefore y= 1 only.

Hope my answer helps you.

Answer 2

Given:

21y5 is a multiple of 9 where y is a digit.

To find:

The value of y.

Solution:

To answer this question, first of all, we should know that if a number is a multiple of 9 or divisible by 9 then the sum of all digits of that number will be multiple of 9 or divisible by 9.

So,

As given, we have,

a number 21y5 is a multiple of 9.

So,

$2 + 1 + y + 5$

should be a multiple of 9

$= 8 + y$

on putting y = 1 we have,

$8 + 1 = 9$

which is a multiple of 9.

As y is one digit, so there are no other values of y for which the given number is a multiple of 9.

Hence, the value of y is 1.