Find the number which is completely divisible by 45.

For a number to be completely divisible by 45, it has to be divisible by 9 and 5

Following are the divisibility rules:

256987 - Not divisible by 5, thus option is wrong

181660 - Sum is 22, which is not divisible by 9

331145 - Sum is 17, which is not divisible by 9

306990 - Sum is 27 and unit digit is 5, thus divisible by 9 and 5 and 45.