The minuend is the number being subtracted from.

A subtrahend is a number subtracted from another.

The difference is the result after subtracting one number from another.

A constant is a quantity that has a fixed value that does not change or vary, such as a number.

An unknown is a quantity that has a set value but it is represented by a symbol or letter.

Use constant difference to balance equations and find unknowns

Maths

In this unit pupils will explain how increasing or decreasing the minuend affects the difference and solve subtraction calculations mentally using known facts explaining how adjusting the minuend can make mental calculation easier In the future unit pupils will explain how to balance equations with addition or subtraction expressions and use their knowledge of balancing equations to solve problems

In the prior unit pupils used the concept of same sum to simplify and solve addition problems  In this unit pupils will explain how increasing or decreasing the minuend affects the difference and solve subtraction calculations mentally by using known facts explaining how adjusting the minuend can make mental calculation easier

Use equivalence and compensation to simplify and solve subtraction problems

Use your understanding of constant difference to work out which of the equations in the sequence is incorrect.

Use constant difference to find the unknown in the equation.
65 − {{ }} = 150 − 111

Use constant difference to find the unknown in the equation.

1,510 − 1,400 = {{ }} − 200

Use constant difference to find the unknown in the equation. 

345,000 − 236,200 = 310,000 − {{ }}

At the gift shop on a residential week, Alex has £13.50 and Sofia has £9.20 to spend. They both buy a souvenir fridge magnet to take home. Sofia now has £6.21 left. How much does Alex have left? 

Match the pairs of number complements to 100

Use a mental strategy to sum these multiples of 100
5,300 + 1,800 = {{ }}

Add together these multiples of 1,000 using a mental strategy.
{{ }} = 117,000 + 19,000

Complete this subtraction using a mental strategy.
367,000 − 24,000 = {{ }}

How much change would I get from £20 if I spent £10.98 on a new football? £{{ }} change.

I have a ball of old plasticine that weighs 655 g and a new jumbo pack that weight 1.4 kg. What mass of plasticine do I have altogether?

This lesson will soon be taken down.

Use constant difference to balance equations and find unknowns

Lesson outcome