6
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
15
18 + 50 = 68
2 and a half
You must be 15 to use a card and 18 to buy one.
There is only one LCM, so it cannot be A lcm, but possibly THE lcm. The LCM of any two (or more) numbers MUST be a multiple of all the numbers. For 15 and 18 the LCM must be a multiple of both 15 and 18. In particular it must be one of the multiples of 18. 18 is an even number, so all its multiples will be even. 145 is an odd number, so it cannot be a multiple of 18 Thus 145 cannot be a multiple of both 15 and 18. Thus it cannot be the LCM of 15 and 18. QED.