What is the GCD for 240 and 285?

Answer 1

Since 3 divides both 240 and 285, it is tempting to start with 3 as a common divisor of both 240 and 285. However, since 3 and 5 both divide 285, and 30 divides 240, we probably should start with 15. Fifteen divides into 240 16 times with no remainder. Fifteen also divides into 285 19 times. Since 16 and 19 are relatively prime to each other, 15 is the greatest common divisor of 240 and 285.