Question

what should be added to 320526 to make them multiple of 9

Answer 1

nothing should be added to make it a multiple of 9

Answer 2

A no. is said to be a multiple if its sum of digits(till single digit) is 9
3+2+0+5+2+6=18
1+8=9
so 320526 is itself a multiple of 9
The no. to be added is thus 0 as it is itself a multiple of 9

hope it helps...