In order to save materials and not waste, the side length of a square must be the common divisor of length and width, and the greatest common divisor of 35 and 50 is 5, so only a square with a side length of 5CM can be selected.

Two methods:

50÷5= 10

35÷5=7

10×7=70 (block)

The second type:

(50×35)÷(5×5)

= 1750÷25

=70 (block)

Are you satisfied? How about adding 30 points?