Well, if I was truly not allowed to use a calculator during any step throughout this problem, I would do the following:
\(264^2=(200+60+4)(200+60+4)=200(200+60+4)+60(200+60+4)+4(200+60+4)\)
There are a lot of friendly numbers here, do you agree? Now, let's continue the expansion.
\(200(200+60+4)+60(200+60+4)+4(200+60+4)=40000+12000+800+12000+3600+240+800+240+16\)
WOAH! That's a lot of terms! I would first rearrange the numbers such that the largest are added to the smallest.
\(40000+12000+12000+3600+800+800+240+240+16\)
You can do addition in any order you'd like. The colors indicate an addition where the result will be friendly and will end in another 0.
Now, just do the addition.
\(40000+12000+12000+3600+800+800+240+240+16=69696\)
I wouldn't do 495 the same way, however. I would break that into \((500-5)(500-5)\). Now, do the same thing like before.
\(500(500-5)-5(500-5)\)
\(250000-2500-2500+25\)
\(245025\)
The square root is where I would hit a barrier, though...