Answer: True
If the digits add to a multiple of 3, then the number is a multiple of 3.
A smaller example would be 2+7 = 9, showing 27 is a multiple of 3. This is confirmed because 9*3 = 27.
Another example: 3+3 = 6, so 33 is a multiple of 3 (confirmed by saying 3*11 = 33).