DRDO Multi tasking staff Model paper 7

A number will be divisible by 9 if the sum of all digits of the number is divisible by 9
Sum of digits of the number = 6 + 3 + 5 + P + 6 + 1 = 21 + P
Sum of digits of the number will be divisible by 9 if P = 6
∴ Value of P is 6