If 31y5 is a multiple of (a) 3 and (b) 9, find the value of y which satisfies the number, where y be any digit. Share with your friends Share 0 Jyotsana Yadav answered this 1 View Full Answer Ritwik Rai answered this if no is divisible by 9 then it will be divisible by 3 to.'so we have to put a digit which makes the sum of the digits divisible by 9. 3+1+5=9 thus if we put 0(then sum=9) or 9(sum=18) then no is divisible by 9 as 9 & 18 are divisible by 9 2