Question

How to do cube root easily
please explain im studying in class 7

Answer 1

Answer:

Step-by-step explanation:

You need to remember the cubes of 1-9.

$1^{3} = 1\\2^{3} = 3\\3^{3} = 27\\4^{3} = 64\\5^{3} = 125\\6^{3} = 216\\7^{3} = 343\\8^{3} = 512\\9^{3} = 729$

See the unit digit in all cubes . This will help to find the cube roots.

If the unit digit of cube is 8 then unit digit of cube root will be 2.

If the unit digit of cube is 7 then unit digit of cube root will be 3.

If the unit digit of cube is 4 then unit digit of cube root will be 4.

If the unit digit of cube is 5 then unit digit of cube root will be 5.

1. Find cube root of 300763‬.

Break the number in two parts three digits ( 300 and 763)

unit digit = 7  (since 763 last digit 3)

ten digit = 6 (Largest cube less than 300)

ans : 67

2. Find cube root of 5,51,368

Break the number in two parts three digits ( 551 and 368)

unit digit = 2  (since 368 last digit 2)

ten digit = 8 (Largest cube less than 551)

ans : 67