the difference of the digits of a two digits number is 1.the number itself is 1morethan 5 times the sum of its digits. if the unit digit is greater than the tens digit.find the number
unit digit --- x
tens digit ---- y
x - y = 1
x = y+1
10y + x = 5(x+y) + 1
5y - 4x = 1
5y - 4(y+1) = 1
y = 5
then x = 6
the number is 56
After reading the first condition, our number had to be one of
12, 23, 34, 45, 56, 67, 78, or 89
In just a matter of seconds we could have picked out the one meeting the
second condition, namely 56