Question

Find the tens digit of the cube root of each of the numbers in Q. No. 15.

 

Answer 1

(i) Let us consider the number 226981.
The unit digit is 1; therefore, the unit digit of the cube root of 226981 is 1.
After striking out the units, tens and hundreds digits of the given number, we are left with 226.
Now, 6 is the largest number, whose cube is less than or equal to 226 ( \[6^3 < 226 < 7^3\]) .

Therefore, the tens digit of the cube root of 226981 is 6.

(ii) Let us consider the number 13824.
The unit digit is 4; therefore, the unit digit of the cube root of 13824 is 4.
After striking out the units, tens and hundreds digits of the given number, we are left with 13.
Now, 2 is the largest number, whose cube is less than or equal to 13 ( \[2^3 < 13 < 3^3\] ) .

Therefore, the tens digit of the cube root of 13824 is 2.

(iii) Let us consider the number 571787.
The unit digit is 7; therefore, the unit digit of the cube root of 571787 is 3.
After striking out the units, tens and hundreds digits of the given number, we are left with 571.
Now, 8 is the largest number, whose cube is less than or equal to 571 ( \[8^3 < 571 < 9^3\] .

Therefore, the tens digit of the cube root of 571787 is 8.

(iv) Let us consider the number 175616.
The unit digit is 6; therefore, the unit digit of the cube root of 175616 is 6.
After striking out the units, tens and hundreds digits of the given number, we are left with 175.
Now, 5 is the largest number, whose cube is less than or equal to 175 ( \[5^3 < 175 < 6^3\]).

Therefore, the tens digit of the cube root of 175616 is 5.