Question

Q3. Find the cube root by estimation method:

a) 2197

b) 389017

c) 175616
d) 571787​

Answer 1

Answer:

2197. = 13

389017. = 67

175616. = 56

Answer 2

$\sf\orange{ QUESTION :- }$

Q. Find the cube root by estimation method:-

$\sf\red{ a) 2197 :- }$

Given no. = 2197

Unit digit of the given no. = 7

• unit digit of the cube of the given no.=3

Number obtained after striking out the three digit from the extreme right ( unit , tens and hundreds digits ) = 2

★ 1³ < 2 < 2³

As 1 is smaller , tens digit of the cube root of the given number = 1

hence = ³√2197 = 13

$\sf\red{ b) 389017 :- }$

Given no. = 389017

Unit digit of the given no. = 7

• unit digit of the cube of the given no.=3

Number obtained after striking out the three digit from the extreme right ( unit , tens and hundreds digits ) = 389

★ 7³ < 389 < 8³

As 7 is smaller , tens digit of the cube root of the given number = 7

hence = ³√389017 = 73

$\sf\red{ c) 175616 :- }$

Given no. = 175616

Unit digit of the given no. = 6

• unit digit of the cube of the given no.=6

Number obtained after striking out the three digit from the extreme right ( unit , tens and hundreds digits ) = 175

★ 5³ < 175 < 6³

As 5 is smaller , tens digit of the cube root of the given number = 5

hence = ³√175616 = 56

$\sf\red{ d) 571787 :- }$

Given no. = 571787

Unit digit of the given no. = 7

• unit digit of the cube of the given no.=3

Number obtained after striking out the three digit from the extreme right ( unit , tens and hundreds digits ) = 571

★ 8³ < 571 < 9³

As 8 is smaller , tens digit of the cube root of the given number = 8

hence = ³√571787 = 83