Which of the following numbers is divisible by 45?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 306990
\(45=5\times9\) and 5 and 9 have no common factor, so a number is divisible by 45 when it ends in 0 or 5 and its digit sum is divisible by 9.
Option (1) 306990 — ends in 0; digit sum \(3+0+6+9+9+0=27\), divisible by 9, so it is divisible by 45
Option (2) 256987 — ends in 7, so not divisible by 5
Option (3) 181660 — ends in 0, but digit sum \(=22\), not divisible by 9
Option (4) 331145 — ends in 5, but digit sum \(=17\), not divisible by 9