# Mixed subtractions

Lesson

## Subtraction

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.

#### Practice question

##### Question 1

Find the value of $867-311$867311

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

### Larger numbers

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.

#### Practice questions

##### Question 2

Evaluate $66123-11524$6612311524.

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.

##### Question 3

Fill in the missing blanks.

1.  $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.

### Outcomes

#### NA3-1

Use a range of additive and simple multiplicative strategies with whole numbers, fractions, decimals, and percentages.

#### NA3-6

Record and interpret additive and simple multiplicative strategies, using words, diagrams, and symbols, with an understanding of equality