Column Subtraction with exchange

Now your child has practiced subtraction in columns without exchange, they are ready to understand why we can exchange a group of tens to add more to the units column.

Explain that when the units digit is not large enough to take away from, they will need to borrow a ten from the tens column to make the units number larger. They must remember to cross out the tens digit they are borrowing from and write the new tens digit in its place.

Watch the clip below to practice with your child.

Column subtraction without exchange

Now your child has a secure understanding of the value of digits within each column they are ready to move to column subtraction without exchange.

This means that the number they are subtracting from has a larger number in the units column than the number they are subtracting.

e.g.      47 – 24 =       or           56 – 31 =

Explain the importance of keeping the sum and the answer in columns  as this will help to prevent mistakes when subtracting .

Watch the clip below to practice this method with your child.

Subtracting multiple jumps of ten on an empty number line

Now your child can subtract one jump of ten, we can move on to multiple jumps of ten.

This is a tricky step as it needs the child to be able to subtract multiples of ten mentally. Again it is important to set out the jumps clearly and remember that the next number needs to be written where the jump touches down on the line.

Watch the clip below to practice this method with your child.

Subtracting a jump of ten on an empty number line

The next stage in subtraction is to take away a jump of ten. Your child needs to have a secure understanding of place value to subtract one ten mentally.

They need to understand that only the tens digit is changed.

e.g. 37 – 10 = 27

The tens column has become less by one ten while the units have stayed the same. This mental strategy is vital and any opportunity you have to practice adding and subtracting tens would be very beneficial.

To help them understand this concept we begin our sum on the right hand side on the number line and jump backwards to reinforce the concept of numbers getting smaller.

To practice this written strategy please watch the clip below.

Subtracting units on an empty numberline

When we introduce subtraction on an empty number line it is important that your child understands that subtraction means the numbers will be getting smaller.

To help them understand this concept we begin our sum on the right hand side on the number line and jump backwards to reinforce the concept of numbers getting smaller.

To practice this written strategy please watch the clip below.