Answer :
You need to subtract the largest number and the smallest, so it would be 12-0, getting an answer of 12.
18, 13, 22, 17, 21, 24}
{17, 19, 22, 26, 17, 14}
{13, 17, 12, 21, 18, 20}
{18, 21, 16, 22, 24, 15}