0For finding out cube root of any number.
You only know the cube of number from 1 to 10 and you are able to answer cuberoot in 20 seconds.
Pre requisite:
13 = 1
23=8
33=27
43=64
53=125
63=216
73=343
83=512
93=729
103=1000
Suppose you want to know cube root of 46656 then you need to follow only 2 steps:-
Step 1: Note last three digits. in our example it is 656.In it note last digit of 456 is as 6.And from cubes note that whose cube makes last digit as 6. In our example 63 = 216. So unit digit of cube root is 6.
Step 2: For tens digit.Check remaining number.In our example 46.Check whether this number is between whose two numbers form list of cubes.
In our case 46 is in between 27 and 64.so keep number as lower and it is 3.
So our answer is 36.
