Question

Question 15

In the given question, out of four options, only one is correct. Write the correct answer.

If $5A\times A=399$, then the value of A is
(a) 3
(b) 6
(c) 7
(d) 9

Answer 1

We have, $5A\times A=399$
Here, $A\times A=9$ i.e. $A\times A$ is the number 9 or a number whose unit's digit is 9. Thus, the number whose product with itselt produces a two-digit number having its unit's digit as 9 is 7.
i.e. $A\times A=49\Rightarrow A=7Now,5\times A+4=39\Rightarrow 5\times 7+4=3939=39$
So, A satisfies the product.
Hence, the value of A is 7.