Question

Fill in the numbers from 1 to 6 without repetition, so that each side of the triangle adds up to 12.

Answer 1

Place the largest numbers, i.e., 4, 5 and 6, at the three corners of the triangle. 

Now, 4 + 5 = 9, 4 + 6 = 10 and 5 + 6 = 11

Therefore, by placing 3 between 4 and 5, 2 between 4 and 6, and 1 between 5 and 6 we get the desired magic triangle.