Question

cube roots estimation method pls explain me ?!! and tell how to do

Answer 1

 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 = 3 6 ).

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 number                     Unit digit of cube root
1                                                                   1
3                                                                   7
4                                                                   4
5                                                                    5
6                                                                    6
7                                                                    3
8                                                                    2


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 ---> 238328 

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 

Answer 2

easily solve the cube roots example:- and solve any questions