There are some shortbreads in a box. The shortbreads can be put into plates of 3 or 6 with no shortbreads leftover. When the shortbreads are put into plates of 12, there are short of 6 shortbreads on the last plate. If there are more than 50 shortbreads but less than 70 shortbreads, how many shortbreads are there in the box?
If shortbreads can be put into plates of 3 or 6 with no shortbreads leftover, the number of shortbreads is a multiple of 6 as 6 is a multiple of 3.

Multiples of 6 that are greater than 50 but less than 70: 54, 60, 66

Multiples of 12 that are greater than 50 but less than 70: 60
Multiples of 12 (- 6) that are greater than 50 but less than 70: 54

Common number = 54

Number of shortbreads = 54

Answer(s): 54