A 1-9 magic square must add to 15.
The answer is 18. To check, plus 18 and 18 to find out.
about 15 or 18 about 15 or 18
18
Cut in half, add one, cut in half, add one and so on.
30 - 6 = 24, 24/2 = 12 which is the lower number, making the other 18.Alternative method: 30 = 15 + 15, difference zero. Add half of 6 to one of the 15s and take half of 6 from the other 15, giving 18 & 12.
-33 and 18
27
15
18 + 50 = 68
15
2 and a half