Question

Find the cube root of $389017$ by finding their units and ten digits.

• A. $63$
• B. $67$
• C. $73$
• D. $77$

Answer 1

The correct option is C $73$

Given, $389017$.

Here, the unit digit is $7.$

$\therefore$ The unit digit of its cube root is $3$.....$[\because 3^3=27]$.

After grouping the last three digits from the right, the number left is $389.$

Now, $7^3=343<389$ and $8^3=512>389.$

$\therefore$The tens digit of the cube root is $7.$

Therefore, $\sqrt[3]{3389017}=73$.

Hence, option $C$ is correct.