A two digit number has 3 in its unit digit. The sum of its digits is one-seventh of the number itself. What is the number?

A 73

B 63

C 53

D 50

Correct Answer: Option B

Let n = tens digit Let m = units digit Then your whole number is N = 10 X n + m……(1) here, n + m = 1/7 X (10Xn + m)……….(2)

the units digit is 3 or

m = 3

Now to solve, put 3 into (2) and get

n + 3 = 1/7 X (10 X n + 3) or, 7 X n + 21 = 10 X n + 3 where simply multiplied both sides by 7.

Or,3Xn = 18 or, n = 6

Therefore your number is from (1)

N = 10X6 + 3 or N = 63