# Factors

A factor is a number that goes into another number. For example, 3 is a factor of 15. Factor pairs are pairs of numbers that multiply to make the number that you are factorising. 3 x 5 = 15 so {3,5} are a factor pair of 15.

Factors are really useful. You will use them when factorising quadratics, in number theory, to find the HCF and LCM of a group of numbers. It is important that you understand how to find them.

Some numbers are special because of properties of their factors. A perfect number is one in which the sum of the factors is exactly twice the number itself. Six has the factors {1, 2, 3, 6} and if you add these, 1+2+3+6=12 which is obviously double 6, so six is a perfect number.

## Lowest Common Multiple

Four questions involving finding the Lowest Common Multiple.

## Questions on Factors

Multiple exam type questions on calculating the prime factors of a number, HCF and LCM of a pair of numbers.

## Exam questions on Factors and Indices

Fractions, indices, factors, HCF and LCM.

## Perfect, Abundant and Deficient Numbers

Finding factor pairs and then investigating to see which numbers are abundant, deficient or perfect.

## Video on Finding the Product of Prime Factors

Video on finding the product of prime factors using a factor tree.

## Assessment on the Product of Prime Factors

Assessment on finding the product of prime factors in various ways based on GCSE maths type questions.

## Erasothenes' Sieve

Erasothenes' Sieve for finding prime numbers. I have arranged it in rows of six so that it is obvious that above 4, all prime numbers are of the form 6n-1 or 6n+1. Obviously, not all numbers of this form are prime.

## Factorising Expressions

Factorising expressions of the type seen on pages 2 to 4 of the exam papers at GCSE. I emphasise the connection between dividing and factorising. It will seem a long winded way on the video, but it is good introduction as the students seem to understand what is going on better.

## Factorising Expressions

Factorising expressions of the type seen on pages 2 to 4 of the exam papers at GCSE.

## Factors and Number Theory

Triangular numbers, polygonal numbers, factors and multiples, HCF and LCM, Division Algorithm, Euclid's Algorithm, Prime Numbers, Goldbach Conjecture. What is there not to love?

## Investigate Prime Numbers and Factors

Ideas, definititions and things to put up on your wall about prime numbers, square numbers, Bertrand and Goldbach's Conjectures, Is one a prime?

## Video on LCM, HCF and Product of Prime Factors

Video on LCM, HCF and Product of Prime Factors.

## Video on LCM, HCF and Product of Prime Factors

Video on LCM, HCF and Product of Prime Factors.

## Video on Factor Pairs

What is a factor pair and how do you work them out? Find some questions on this subject here.

## Video on Product of Prime Factors

How to calculate the product of prime factors.Find some questions on this subject here.

## Video on calculating lcm and hcf using a Venn diagram

Video on calculating lcm and hcf using factor trees and a Venn diagram.Find some questions on this subject here.

## Video on calculating lcm and hcf using a Venn diagram

Video on calculating lcm and hcf using factor trees and a Venn diagram.Find some questions on this subject here.

## Maths Questions on Prime Factors

Maths Questions on Prime Factors. The last four videos are designed to help with this work if you get stuck.

## Prime Factors Explained

Prime Numbers, Prime Factors, Highest Common Factor and Lowest Common Multiple

## Questions on Prime Factors

Questions on Prime Factors.

## Revision on Factors

Questions on Prime Factors, factor pairs, HCF and LCM, GCD, HCF and LCM problems, Factorising into a single bracket.