A two-digit number is such that the product of the digits is 8. When 18 is added to the number, then the digits are reversed. The number is:

– by
Question:
A two-digit number is such that the product of the digits is 8. When 18 is added to the number, then the digits are reversed. The number is:

[A].

18

[B].

24

[C].

42

[D].

81

Answer: Option B

Explanation:

Let the ten’s and unit digit be x and 8 respectively.
x
Then, 10x + 8 + 18 = 10 x 8 + x
x x

10×2 + 8 + 18x = 80 + x2

9×2 + 18x – 72 = 0

x2 + 2x – 8 = 0

(x + 4)(x – 2) = 0

x = 2.