Question

The digit in the unit's place of a number is equal to the digit in the tens' place of half of that number and the digit in the tens' place of that number is less than the digit in unit's place of half of the number by 1. If the sum of the digits of the number is seven, then what is the number?

• A. 52
• B. 16
• C. 34
• D. Data inadequate

Answer 1

The correct option is A 52

Let $\frac{1}{2}$ of the number = 10x+y and the number = 10V +W
From the given conditions, W = x and V = y-1
Thus, the number = 10(y-1)+x
Now, 2(10x+y) = 10(y-1)+x
$\Rightarrow 8y-19x=10$ ..........(1)
Also,
$V+W=7\Rightarrow y-1+x=7$
$\therefore$ x +y = 8 ........(2)
Solving equation (1) and (2), we get
x = 2 and y = 6
So, Number = 10(y-1)+x = 52.
Alternate Method:
Use options & check for the given conditions.