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easy maths question

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easy maths question

by GMAT? » Thu Dec 06, 2007 8:59 am
hi,

why does the cubic root of 0.000064 = 0.04

why does the square root of 0.04 = 0.2

I having difficultly in determining how many decimal place to move the answer after the cubic and sqaure roots are done, i.e. cubic root of 0.000064 = 0.04 and why not 0.004, etc.

thanks
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by mschling52 » Thu Dec 06, 2007 10:43 am
When you multiply decimals together, the product will have as many digits to the right of the decimal as do the factors combined. For example,

.2 * .2 = .04

because the two factors each have 1 digit to the right of the decimal. Therefore, the product will have 1+1 = 2 digits to the right.

Similarly, .04*.04*.04 = .000064 because each of the 3 factors has 2 digits to the right of the decimal, so the product has 2+2+2 = 6 digits to the right.
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by xcise_science » Thu Dec 06, 2007 10:53 am
I have a similar problem.
When I'm not sure, I just think of it as a regular multiplication (which it is anyway) and just count the # of decimal places in the number I'm multiplying.

So, for the cubic root of 0.000064 ==> 0.04.
when you multiply .04 by itself 3 times, you have to move the decimal 6 places to the left (2 decimal places in .04 * 3 times).

Likewise for the square root of 0.04 = 0.2, if you multiply that twice you get .04



I think this was the answer to your question
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