If 51x3 is a multiple of 9, where x is a digits, then what is the value of x?
We have the sum of the digits of 51x3
= 5 +1 + x + 3
= 9 + x
Since, 51x3 is divisible by 9.
∴ (9 + x) must be divisible by 9,
∴ ( 9 + x) must be equal to 0 or 9 or 18 or 27 or ....
But s is a digit, then
9 + x = 9 x = 0
9 + x = 18 x = 9
9 = 27 x = 18, which is not possible
∴ The required value of x = 0 or 9.
Write the following numbers in usual form:
(i) 7 x 100 + 10 x 5 + 9 x 1 (ii) 4 x 100 + 10 x 0 + 7 x 1