A magic triangle has three numbers on every side.
The three numbers on each side always add up to the same sum.
We call this same sum the target sum.
It is written above the triangle (for example: sum = 10).
Example: target sum 10
In the three corners are 1, 2 and 3.
On every side one number in the middle is still missing.
Left side: 1 and 2 are there, the 7 is missing (1 + 7 + 2 = 10).
Right side: 2 and 3 are there, the 5 is missing (2 + 5 + 3 = 10).
Bottom side: 3 and 1 are there, the 6 is missing (3 + 6 + 1 = 10).
The numbers filled in show the solution.
Example
For parents
What does this exercise practice?
Arrange numbers so that every side gives the same sum, practicing clever adding and completing.
Common pitfalls
Children often work out only one side and forget that all three sides need the same sum. It helps to check every side separately and compare.
How to practice at home
Lay out three small cards as corners, then fill the sides with more cards until every side gives the same amount. Building blocks make trying it out easier.
Related: Magic square, Calculation, Number house