Question

the unit digit of a two - digit number is 3 and seven times the sum of the digit is the number itself.find the number?

Answer 1

let the no. be p3 or
we can write it as (10×p + 3) in expanded form
sum of digit will be p + 3
now according to question seven times of sum of digit is no. itself so,
7(p+3)=10×p + 3
7p +21=10p +3
18=3p
p=6
therefore no. is 63