<p>okay it is number 15....
SAT</a> Prep: Test 5 Section 7 Part 4 | Khan Academy</p>
<p>number 15 starts at 8:28</p>
<p>I got the squares down like the squares of the numbers of 1-10,
but why did he subtract 100-10? something bout perfect squares....(someone explain in detail please)
which is equal to 90(E)</p>
<p>The question is asking how many numbers are NOT perfect squares between 1 and 100.</p>
<p>1^2 through 10^2 (10 #'s) are all perfect squares between 1 and 100 (100 #'s). So, the numbers that are NOT perfect squares are just your total (100) minus how many perfect squares you DO have (10), which equals 100 - 10 = 90.</p>