Question

what is a five digit number less than 25,000 if each digits' value is one less than the digit to its right and is divisible by two and four

Answer 1

A number is divisble by 4 if its two right-most digits are divisible by 4
So our number can only end in
12 , 16, 24, 28, 32, 36, 40, 44, 48, 52, 56, .... ,
remember that each digit in the whole number is such that it is 1 less than the digit on its right
only 56 fits that pattern

so clearly the entire number must be
23456