Question

What is $15$ times $15$?

Answer 1

Hint: To solve the question we need to know the concept of roots and powers. We need to multiply the given number to find the value of the square of the given number. Square of a number is when a number is multiplied to itself once. The formula used here is $a\times a$ which is equal to ${{a}^{2}}$, where it would have a result as ${{a}^{2}}=b$.

Complete step by step solution:
The question asks us to find the value of $15$ times $15$. It has another approach too which is, for a number when being multiplied by the same number, an exponent could be used as given in the question. We are required to multiply $15$ with $15$ .
Since $15$is being multiplied to $15$, which means same number is being multiplied twice, so we can apply the formula of square which is
 $\Rightarrow {{15}^{2}}$
On calculating the number we get:
$\Rightarrow 225$

$\therefore $ $15$ times $15$ is $225$.

Note: We can check whether the square of the number is correct or not by finding the square root of the answer. So on doing so , we get
$\sqrt{225}$
Square root of the number $225$ is found by prime factorisation $225$. The prime factors whose product results to $225$ is:
$\Rightarrow 225=3\times 3\times 5\times 5$
Taking it under the root we get:
$\Rightarrow \sqrt{3\times 3\times 5\times 5}$
In case of square root if any number is being multiplied twice then only one number of it is considered and the root sign is removed. On doing this we get:
$\Rightarrow 3\times 5$
$\Rightarrow 15$
Since the number after finding the square root the cube root comes to end up with the same value as that is given in the question, which is $15$. So we can infer that our answer is correct.