shrutib wrote:(-20)to the power 24, (sorry i couldn't find superscript here.) = 16* 10 the power 30.
I'll add my two cents on this.
BTW, the carot symbol (^), Shift-6, is typically used for exponents in plaintext, such as we have in these posts.
First of all,
(-20)^24 = (20)^24
because even powers of a negative are positive. Next
(20)^24 = (2*10)^24 = [2^24]*[10^24]
because exponents distribute over multiplication.
The 10^24 part is easy.
For 2^24, let's use a shortcut, the same shortcut they use in Computer Sciences.
2^10 ~ 1000 (what is called "kilo" in CS)
2^20 ~ 100000 (what is called "Mega" in CS)
Therefore,
2^24 = (2^4)*(2^20) ~ 16 * 10^6
and therefore
(-20)^24 = (20)^24 = [2^24]*[10^24] = [16 * 10^6]*[10^24] = 16*10^30
That part about approximating high powers of 2 is probably more advanced than you would need on all except possible the most difficult 800 level questions. The related laws of exponents facts, though, are good meat-and-potato Quantitative skills.
Does all this make sense?
For practice, here's another different sort of powers question
https://gmat.magoosh.com/questions/300
When you submit your answer, the following page will have the complete video solution.
Please let me know if you have any further questions.
Mike
