Count every square, small and large, in a grid of 3 rows and 4 columns of equal squares.

Explanation

1. 01

   $1 \times 1$ squares: $4 \times 3 = 12$.

2. 02

   $2 \times 2$ squares: $3 \times 2 = 6$.

3. 03

   $3 \times 3$ squares: $2 \times 1 = 2$.

4. 04

   Total $= 12 + 6 + 2 = 20$.