Question 769912
Put all possible values (starting from 0 upwards) in the 1's place.
Find out what the corresponding 10's digit would be - 1's place digit + 4.
Obviously if unit digit + 4 crosses 9, it is not valid. It has to be less than
or equal to 9.
So you have only the following numbers possible:
40, 51,62,73,84 and 95!
:)