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⁞ Problems On Numbers

Aptitude ➤ Problems On Numbers ➤ 1

In this section, questions involving a set of numbers are put in the form of a puzzle. You have to analyze the given conditions, assume the unknown numbers and form equations accordingly, which on solving yield the unknown numbers.

Question 1
Q1.  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 :
 

Answer :  24


Let the ten's and unit digit be x and (8/x) respectively.
Then, [10x + (8/x)] + 18 = 10 x (8/x) + x
⇒ 10x2 + 8 + 18x = 80 + x2
⇒ 9x2 + 18x - 72 = 0
⇒ x2 + 2x - 8 = 0
⇒ (x + 4)(x - 2) = 0
⇒ x = 2.

∴ The number is 24.
⚔ DISCUSS

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