    Question

# How to find a cube root ?

Open in App
Solution

## Let me explain this with the help of an example. Say, we need to find the cube root of 4913 Step 1: Identify the last three digits and make groups of three three digits from right side. That is 4913 can be written as 4, 913 Step 2 Take the last group which is 913. The last digit of 913 is 3. If the last digit of the perfect cube = 3, the last digit of the cube root = 7 Hence the right most digit of the cube root = 7 Step 3 Take the next group which is 4 . Find out which maximum cube we can subtract from 4 such that the result >= 0. We can subtract 1³ = 1 from 4 because 4 - 1 = 3 (If we subtract 23 = 8 from 4, 4 - 8 = -4 which is < 0) Hence the left neighbor digit of the answer = 1. That is , the answer = 17 Another example- Cube Root of 804357 Step 1: Identify the last three digits and make groups of three three digits from right side. That is 804357 can be written as 804, 357 Step 2 Take the last group which is 357. The last digit of 357 is 7. Remember point 2, If the last digit of the perfect cube = 7, the last digit of the cube root = 3 Hence the right most digit of the cube root = 3 Step 3 Take the next group which is 804 . Find out which maximum cube we can subtract from 4 such that the result >= 0. We can subtract 93= 729 from 804 because 804 - 729 = 75 (If we subtract 10³ = 1000 from 729 , 729 - 1000 = -271 which is < 0) Hence the left neighbor digit of the answer = 9 That is , the answer = 93 Another basic method is by prime factorization of the number. Say 4913, 4913=17×17×17 So, cube root of 4913 is 17.  Suggest Corrections  1      Similar questions  Related Videos   Cube Roots
MATHEMATICS
Watch in App  Explore more