When you add 18 to 1/4 of a number you get the number itself

- - Then when you only have 1/4 of the number, 18 must be

the missing 3/4 of it.

- - If 18 is 3/4 of it, then each quarter of it is 6.

- - When you have all 4 quarters in the same place, if each one is 6,

then the whole thing must be 24.