155777

To solve:
1. Write out all the given shape problems
2. Write out numbers 0 to 12, with space to fill in the corresponding shapes
3. I then used trial and error, solving first problem a (3 x 4 = 12)
4. After solving problem a, I filled in the values 3, 4 and 12 for their shapes.
5. From here it is possible to work the remainder of the problems, using the same technique.
• The values that are not included in the final answer (as there were only 11 out of a possible 13) are 7 and 11.