NZ Level 3 Add and subtract four digit numbers II
Lesson

Earlier, you learned that you can regroup $10$10 units to make $1$1 ten and $10$10 tens to make $1$1 hundred.  Then, you were able to use this regrouping to add and subtract $3$3 digit numbers more easily.

You can also regroup $10$10 hundreds to make $1$1 thousand. ## Regroup and carry over to add

When adding numbers in one place value, look out for sums of $10$10 or more.  Use regrouping to carry groups of ten to the next highest place value.  Watch the video below to see how.

Remember!

It may be easier to add if you regroup and reorder your numbers. Go back to Regrouping Numbers to Add and Subtract to review.

## Regroup and borrow to subtract

When subtracting numbers in one place value, make sure that you have enough to subtract.  Use regrouping to replace $1$1 of a higher place value with $10$10 of the lower.  Watch the video below to see how.

Remember!

When subtracting using columns, always start with the units and work up in case you need to regroup.

#### Worked Examples

##### question 1

Using the fact that $7060=7000+60$7060=7000+60 and $2040=2000+40$2040=2000+40, evaluate $7060+2040$7060+2040.

##### question 2

Find the value of $4025+1075$4025+1075.

##### question 3

Solve $2221-1391$22211391.

### 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