MATH TRICKS TO FIND OUT CUBE ROOT

Description:

You can easily guess any cube root up to 200 by looking at the last number of the cube and knowing the cubes from 1 to 20.

So for example, if somebody yells out, "3,511,808 !", I immediately know that it is 152 cubed!! How did I do this?

Well, if the last number is 0,1,4,5,6 or 9 it stays the same. As for 2,8 and 3,7 they simply reverse each other. Then cross out the last 3 numbers look at what's remaining and this will be somewhere between one of the first 20 cubes we memorized in this test which gives you the first number of your cube root.

So when the spectator yelled out "3,511,808" I looked at the last digit and saw that it was an 8 which immediately means the last number of our cube root is going to be a 2 (because 8 and 2 always switch each other as explained above) So remember your 2 and move on to the last step.

Next I crossed out the last 3 digits which is the "808" in "3,511,808" leaving me with 3,511. Now this number falls between any of our cubes we are studying in this list. In this case I know that 15=3,375 and 16=4,096 so our leftover number of 3,511 clearly falls between them meaning the beginning of our cube root has to be less than 16 but more than 15 so the answer is 15 because remember our very first number we figured out by looking at the last digit which ended up being 2? well you just stick that on the end of the 15 so your answer is 152 !! So that explains how the number fell between 15 and 16 because really it's falling between 150 and 160.

One last quick example to show how fast it goes (because this goes almost instantaneously fast when you practice a couple XD):

Here's our new number to guess the cube root of between 1 and 200. "2,924,207"

look at the last digit 7 (switches with 3). Cross out 207 and all we have left is 2,924 which falls between 14 and 15 so it has to be 14. put the 14 and the 3 together and our amazing answer is 143!

One last one real fast. "7,880,599" last num 9=9. cross out 599, 7,880 is between 19 and 20. Answer is 199.

Easy enough right? We'll see o.0(see less)