Question

Find the cube root of the following number by finding their units and ten digits: 46656
A. 36
B. 31
C. 32
D. 35

Answer 1

Hint: Observe the unit’s digit of the given number, and think of a number whose cube will have that digit as its unit digit. Next step is to hide the 2 digits in the left and consider the first 2 digits of the number, think of a number whose cube will be less than the number given in the question.

Complete step-by-step answer:

46656 – Here the unit digit is 6.

Therefore, the unit digit of the cube root is 6. $\left[ {{6^3} = 216} \right]$

After striking out the last three digits from the right, the number left is 46.

Now, ${3^3} = 27 < 46\,and\,{4^3} = 64 > 46$

Therefore, the ten’s digit of the cube root is 3.

Therefore, $\sqrt[3]{{46656}} = 36$

Option A is the correct answer.

Note: Cube of a number is a number when we multiply the number with itself thrice. To find the cube root the first step should be to focus on the last digit and then the first two digits.