Credit for this problem goes to Vittoria Sasso. Thanks!

## Four Fours

Can you make all of the numbers from 1 to 20 using exactly four fours and the operators, +, -, *, /, factorial.

Four example, here are two valid ways to make 0:

\[4 - 4 + 4 - 4\] \[(4 + 4) \cdot (4 - 4)\] Solution