Lesson

Many of the strategies we use for addition problems are also useful for subtraction problems. Place value is really important, and number lines also work really well with subtraction, and they help us visualise what we are actually solving. In the first video, we'll work on some subtraction problems, with and without a number line.

Find the value of $867-311$867−311

8 6 7 - 3 1 1 $\editable{}$ $\editable{}$ $\editable{}$

We can write our problem out vertically when we have more digits, and when we think we need to use regrouping with our place value. Let's see how working vertically can help when we have more digits in our number, in this video, as well as check whether our answer seems reasonable.

Evaluate $66123-11524$66123−11524.

In the next question, we might solve it using a vertical algorithm. We could also partition our number, using place value, and solve it that way.

Fill in the missing blanks.

$8$8 $\editable{}$ $9$9 $\editable{}$ $-$− $\editable{}$ $1$1 $\editable{}$ $2$2 $3$3 $1$1 $5$5 $7$7

Don't forget to line up your numbers

When you use a vertical method of subtraction, be sure to line up your place value digits. Ruling lines can help, if digits seem to be all over the place.

Solve problems involving the addition, subtraction, and multiplication of whole numbers, using a variety of mental strategies (e.g., use the commutative property: 5 x 18 x 2 = 5 x 2 x 18, which gives 10 x 18 = 180)