BIDMAS
You need to follow the order of operations BIDMAS, otherwise the answer can be  completely wrong. Pay close attention when there is more than one sign or operation.
Averages and Range
Averages are used to give an overview about a large set of data. The mean, median, mode and range are all types of averages that we can find.
Product of Prime Factors
To find the product of prime factors, you need to divide a number using a factor tree to establish the prime factors, then use indice notation to display this. These are useful for HCF and LCM.
Highest Common Factor and Lowest Common Multiple
We are looking for the highest number that can be divided into two numbers, and the lowest number they can both go into. Use a factor tree to find the product of prime factors or then a venn diagram.
Standard Form
Standard form is used to present numbers using powers of 10. The number must be between 1 and  10.