Question

A two digit number is 4times the sum of its digits

Answer 1

let the digits be x,y 

so 10x+ y = 4(x+ y)

⇒ 2x = y

so all the numbers whose units digit is 2 times the tens digit holds the condition 
the number is 4 times the sum of digits for eg 12,24,36,48 (only possible pairs) ANSWER