How to solve the mutiple of 3 from 15 to 45 Answer: 15, 18, 21, 24, 27, 30, 33, 36, 39, 42, 45 Step-by-step explanation: List down all the multiples of 3. (Write down 3 first then continue adding 3.) Then, seperate the numbers/multiples that is atleast 15 to 45. Multiples of 3: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42, 45