Since 30² = 900 and 40² = 1600, between 30 and 40 of the numbers Grogg enters will reduce to integers. Now just find which count is correct. We don't have to look far:
31² = 961
32² = 1024
so there 31 of the outputs of √1, √2, √3, ..., √1000 are integers.
B because you multiply 7 times 4 that’s 28 then times 5 that’s 140 so for b you do 5 times 7 that’s 35 then times 4 that’s 140 so b is the correct answer, hope it helps