Multiples and factors.
Multiples: The multiples of a number are just its time table.
Factors: The factors of a number are all of the numbers that divide into it.
Finding prime factors - the factor tree
1)Start with the number at the top.
2) start splitting it into factors - for example say your number is 420 42 and 10 are factors.
3) then start splitting these numbers into factors - 6 and 7 make 42 5 and 2 make 10
4) keep going until you're only left with prime factors then times the prime numbers and write them out in order.