# Solubility ? with cube roots

10+ Year Member
I really do not understand how to mentally solve cube roots. For example

2.1 x 10-6=4x3

so you divide by 4..i understand that. But when it gets to cube I dont know how to do that by hand.

.525 x 10^-6 =x3

so how do you figure out the cube root of .525 x 10-6 ???

#### matth87

I really do not understand how to mentally solve cube roots. For example

2.1 x 10-6=4x3

so you divide by 4..i understand that. But when it gets to cube I dont know how to do that by hand.

.525 x 10^-6 =x3

so how do you figure out the cube root of .525 x 10-6 ???

First I would convert .525 x 10^-6 to 525 x 10^-9
Then the cubed root of 10^-9 = 10^-3, you just multiply by 1/3.

Then I would try to find out which 3 numbers multiply together to get close to 525

7x7x7 = 343
8x8x8 = 512

So it has to be a little more then 8. so 8x10-3

10+ Year Member
very clever!!!!

#### G1SG2

10+ Year Member
5+ Year Member
First I would convert .525 x 10^-6 to 525 x 10^-9
Then the cubed root of 10^-9 = 10^-3, you just multiply by 1/3.

Then I would try to find out which 3 numbers multiply together to get close to 525

7x7x7 = 343
8x8x8 = 512

So it has to be a little more then 8. so 8x10-3

#### matth87

very clever!!!!

Yeah approximations take a little bit of cleverness lol.

#### hopslam

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10+ Year Member
stone cold

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