Question

how many can ans this simple question

Answer 1

total number of square
$= {4}^{2} + {3}^{2} + {2}^{2} + {1}^{2} \\ = 16 + 9 + 4 + 1 \\ = 30$

4 by 4 ,1 unit side square
3by 3 , 2unit side square
2 by 2, 3 unit side square
and
1 by 1, 4 unit side square