If the number with the digits reversed can have a leading 0 so that it is a 1-digit number, then 16. Otherwise 13.
5 is a factor of any whole number ending in 5; it is also a factor of any whole number of 2 or more digits ending in zero.
This cannot be answered. This will have to be written to where it can be understood.
Factors go into numbers, numbers go into multiples. A multiple is divisible by a number, a number is divisible by a factor.
Digits is how many numbers you have in a number. If you have the number 4 it has one digit if you have the number 20 it has two digits and if you have the number 558 it has three digits. So basically in the number 1085 it has 4 digits because there is 4 numbers in it, the numbers are 1,0,8 and 5. Hoped you understand.
The original number would be 28. Swapped around, the number's digits are 82. The difference between the two numbers is 54.
9 on apex
Not a lot. They're both prime numbers. A factor that is prime is used to make other numbers.