Answer: 2460
Step-by-step explanation: Used a calculator, and added from 3 x 1, since the answer is the first 40 positive multiples.
Another way is: 3 + 6 + 9 + ... + 120. There are 40 numbers, so 20 pairs of 123. 123 x 20 + 2460 :)
HOPE THIS HELPS <3