Aptitude - Problems on Numbers - Discussion

Discussion Forum : Problems on Numbers - General Questions (Q.No. 5)
5.
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:
18
24
42
81
Answer: Option
Explanation:

Let the ten's and unit digit be x and 8 respectively.
x

Then, 10x + 8 + 18 = 10 x 8 + x
x x

10x2 + 8 + 18x = 80 + x2

9x2 + 18x - 72 = 0

x2 + 2x - 8 = 0

(x + 4)(x - 2) = 0

x = 2.

Discussion:
43 comments Page 5 of 5.

Mitun C Das said:   8 years ago
Answer is absolutely 24. I agree.
(1)

Anwar said:   9 years ago
Why we take x and 1/8 explain?

Krans said:   1 decade ago
Can you said in another way?


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