Question

Find the resulting number.
Take a number 72
Add 3 and then reverse it.
A.72
B.73
C.72
D.57

Answer 1

Hint: Add the number and then reverse the order of its digits. For reversing the digits its unit’s place digit is replaced by hundreds place and hundreds place is replaced by unit’s place for a two digit number.

Complete step-by-step answer:
Any two digit number say $ XY $ .
It can be written as $ 10X + Y $ .
Here $ X $ is the ten’s place digit and $ Y $ is the unit’s place digit.
 On reversing the digits the number becomes $ 10Y + X $ .
Here
 $ Y $ comes to ten’s place and $ X $ comes to the unit's place.
The given number is $ 72 $ .
We are required to add $ 3 $ in the number $ 72 $ ,
The number $ 72 $ becomes as $ = 72 + 3 = 75 $
For reversing the number its digits should be interchanged.
For a 2 digit number, one’s place digit is placed on tens place and tens place digit is placed on one’s place.
$\Rightarrow$ After reversing the order of the digits the number becomes $ = 57 $
So, the correct answer is “Option D”.

Note: The important point is the reversing of the number.
For instance consider a two digit number $ 23 $ , on reversing the digits it becomes as $ 32 $ .
Here we have reversed the unit’s place digit with ten’s place digit and ten’s place digit with unit’s place digit.