Question

the cube root of a number can be found by estimation true or false​

Answer 1

Answer:

true

Step-by-step explanation:

We know that 2 comes at the unit's place of a number only when it's cube root ends in 8. So, we get 8 at the unit's place of the cube root. Now, cube of 4 is 64 and cube of 5 is 125. ... So, in this way, we can find the cube root of a number using estimation method.

Answer 2

Answer:

True

Step-by-step explanation:

The cube root of a number can be found by estimation if it is a perfect cube by unit digit method.

Here is the method:)

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 6 3 =216 and 7 3 =343 .

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

∴ ∛238328 = 62