Question

if you multiply me by 2 I become a number greater than 20 and less than 40.
if you multiply me by 6, i end in 8
if you multiply me by 4 i end in 2

Answer 1

The answer is 13.

13 times 2 = 26

13 times 6 = 78

13 times 4 = 52

Answer 2

13