Answer:
20
Step-by-step explanation:
Each square is a square unit. So just count the squares!
And what about the cut parts that don't take the full square? It's half of the square, so just count as 1/2
So, 1 2 3 4, ___ 5 6 7 8, ___ 9 10 11 12, ___ 13 14 15 16, ___ 17 18, ___ 18 + 1/2 + 1/2 = 19, ___ 19 + 1/2 +1/2= ..... 20 !
