If you divide a number into 3 equal groups and then divide each group in half, you end up with 13. The starting number is.

The starting number is 78.

Explanation:

(x / 3) / 2 = 13

divide a number by 3 (x / 3)

divide in half (x / 3) / 2

You get 13 (x / 3) / 2 = 13

Reverse the problem.

13 * 2 = 26

26 * 3 = 78

x = 78

Plug in the number.

(78 / 3) / 2 = 13

78 / 3 = 26

26 / 2 = 13