Question

Find the cube of 34.

• A. 50864
• B. 38304
• C. 39304
• D. 44304

Answer 1

The correct option is C 39304

We will use the below formula to find the cube of a two-digit number.
${(a+b)}^3$ = $a^3+3a^{2}b+3a{b}^2+b^3$
Step 1 - Find the cube of the ten's digit.
Step 2 - Find 3 times the product of ten's digit${}^2$ and unit digit.
Step 3 - Find 3 times the product of unit digit${}^2$ and ten's digit.
Step 4 - Find the cube of the unit digit.
Step 5 - Keep the unit's digit in every step and carry forward the ten's digit to the next number.
$3^3=27$,
$3\times 3^2\times 4=108$,
$3\times 3\times 4^2=144$,
$4^3=64$. 6 will be carried forward and added to 144.
Now, 144+6 = 150, 108+15 = 123, 27+12 = 39.
So, ${34}^3$ = 39304.