Hey everyone..
I just took a practice GRE and I’m not sure how to (quickly) solve the following questions without a calculator..any help would be greatly appreciated.

1) Which is larger: 100,210 X 90,021 or 100,021 X 90,210
…I know how to multiply them (obviously) but there has to be some quicker way!

2) Which is larger: Sqrt(10)XSqrt(5) or 7.

The only way that I was able to figure this one out was to simplify it to 5XSqrt(2) and then "roughly" multiply 1.41X5. Is there not a more simple way to find this answer?

3) Which is larger: The greatest Prime Factor of 3^5 or the greatest Prime Factor of 5^3

any help on any of these problems would be greatly appreciated!

I heard there have been a few changes implimented when taking the Graduate Record Examination. Are test takers allowed to use a calculator on the general exam?

Are you allowed to use a calculator on the GRE Subject test in mathematics !?!?!?!? If so, is the TI-89 Titanium allowed?

I’m pretty handy with my shortcuts in math but is there something I’m missing here?

Mary received a net of 5 that was 65% of her gross paycheck.
A- Mary’s gross paycheck
B- 0

The answer is they’re the same, but how are you supposed to figure that out without a calculator?