Question 91

In a two digit number the digit in the unit’s place is twice the digit in the ten’s place and the number obtained by interchanging the digits is more than the original number by 27. What is 50% of the original number ?

Solution

Let the number be equal to XY.
Hence, it's value equals 10X+Y
And the value of the number obtained by reversing the digits is 10Y+X

Their difference equals 9Y-9X which equals 27
Or, Y-X = 3

We also know that Y=2X. Hence, X=3 and Y=6

Therefore the original number is 36 and half of it equals 18

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