Question

find cube root of 300763 by estimation

Answer 1

Estimating Cube Root, this method will work only if the given number is a perfect cube. The following are the steps to estimate the cube root.



Step I : Make groups of 3 digits from unit(one's) place.This the 1st group.The remaining number makes the 2nd group.

Step II : The unit's digit of the 1st group will decide the unit digit of the cube root.( if the unit digit of the cube is 6 then the unit digit of cube root will also 6 as 6 x 6 x 6 = 36).

Step III : Find the cube of numbers between which the 2nd group lie.

Step IV : Take the smaller number as its ten's digit.
Unit digit of a given numberUnit digit of cube root11374455667382
Examples on estimating cube root :

1) Find the cube root of 238328.

Solution :
238328 is an even number so its cube root has to an even number.
Make two groups ---> 238 328 

First group 328 ---> unit digit is 8 so unit digit of cube root will be 2. 
(see the above table).

Second Group 238 -----> it lies between 63=216 and 73 =343 .

So take the smaller number 6 as ten's place.

∴ ∛238328 = 62 hope it will help you. I don't know exact answer but I know that it will help you.