Estimating Cube Root
by Sai Praneeth 8A

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 1: Make groups of 3 digits from unit’s place. The first 3 digits from unit’s place will be the first

group. The next 3 digits make up the second group.

Step 2: The unit’s digit of the first group will decide the unit digit of the cube root. (If the unit digit of the cube is 6 then the unit digit of the cube will be 6 as 6*6*6=36)

Step 3: Find the cube root of the numbers of the second group.

Step 4: Take the smaller number as it’s tens digit.

1	1
2	8
3	7
4	4
5	5
6	6
7	3
8	2

 

This table shows the unit digit of a given number and its unit digit of cube root.

Example

Find the cube root of 238328

Solution:

238328 is an even number so its cube root has to be an even number.

Make 2 groups 238 328

First Group- 328 unit digit is 8 so unit digit of cube will be 2.

Second Group- 238 it lies between 6cube=216 and 7 cube= 343

So take the smaller number 6 as tens place

Therefore cube root of 238328= 62