Question

find the least number between 200 and 500 which leaves a remainder of 3 in each case when divided by 8,10,12 and 30

Answer 1

the LCM of (8, 10, 12, 30) = 120
so, it is 2 * 120 = 3 = 243

Answer 2

why you have multiplied it by 2?

Answer 3

He multiplied by 2 bec you need the number to be between 200 and 500
Since the LCM of the 4 numbers is 120, 120 + 3 = 123 is the smallest number that satisfies the rquirement of leaving a remainder of 3, but 123 is not between 200 and 500.
By multiplying 120 by 2, you get 240. Then you add 3 to get 243, and now the number is between 200 and 500.