Definitions from a mathematical mouse

subtraction: the process of taking away one number/amount from another number/amount, which finds the difference between them.

My Youtube videos below demonstrate how to understand formal methods for subtraction. Hope you enjoy them and watch them as many times as you need until you become really confident that you fully understand them!

Of course, you as a great mathematician already know that sometimes using mental methods can be the best strategy and sometimes using formal methods is the best method. Don't always use the same approach - use the best approach!

TdM Brie-Anna de Mouse, creator and star of Maths with a Mouse

Before we get started with formal methods, perhaps you need to brush up on your mental addition and subtraction skills or simply want to play some great addition and subtraction games. If you do, put the big yellow button now!

Subtraction without decomposition

Subtraction with decomposition

Ready to use what you have learned again? Have a go at these great Brain Workouts from mathplayground.com. Try to use your understanding of formal subtraction this time to help find solutions.

Warning: it might not be that easy...again!

Subtraction with same number of decimal places

Subtraction with differing number of decimal places

Subtraction: counting on

Subtraction using constant difference

Below is a great tool from ictgames.com which is ideal for demonstating how constant difference works.

Top tip: To move the difference to another place on the number line, drag the number line, which alters the calculation. This ensures that the difference does not change - it remains constant!

Terrific triangles - addition and subtraction

Understanding the relationship between addition and subtraction is a vital skill so top marks to Topmarks for providing us with Number Fact Families!