There are many ways to introduce and express numbers as a product of prime factors but recently I have been looking at questions that use prime factor form.

I’m not including HCF or LCM in this because most teachers have used PFF to solve HCF and LCM problems before.

Here are some questions I have written that can be solved easily using PFF

These are on the ppt below

I also like this activity I made, its simple practice but saves paper if you display it as a ppt

Update

I made this starter to use with year 10

UPDATE! Prime Factor Form Challenge. The idea is students are faced with increasingly more challenging PFF questions. They need to think about divisibility to help them and they know the numbers are listed below. It can generate some interesting discussions about numbers/divisibility. Students who are faced with a large number that isn’t divisible by 2, 3 or 5 may believe the remainder is a prime number. Once the number is written in PFF they can asign the correct letters and unscramble the word.

Here is the ppt for PFF pff

I was thinking about the factors particular numbers and considered how many factors int he numbers from 1-40. When I reached the 30s I was surprised how many numbers could be written as a product of two primes, meaning they have 4 factors in total. So I started wondering about what students would make of it. Would they realise if the number was written as a product of two primes it would have 4 factors and would they realise you could easily find a number with 4 factors by multiplying 2 primes together.

33=3×11

34=2×17

35=5×7

38=2×19

39=3×13