Primary 3 Addition and Subtraction Within 10 000 Study Guide

Primary 3 addition and subtraction in four short steps: adding in columns, subtracting across zeros, mental sums with a nearby tens number, and working backwards in word problems. Try a question after every step, then work through five examples.

Start here

How do you add and subtract numbers up to 10 000?

Line up the places, then start with the ones.

Thousands, hundreds, tens and ones each sit in their own column, ones under ones. When adding gives a place 10 or more, 10 of it are renamed as 1 of the next place up. When a place has too few to subtract from, 1 of the next place up is renamed as 10.

In this chapter, your child uses this to:

  • add numbers up to 4 digits, renaming as needed;
  • subtract, renaming across zeros in numbers such as 5006;
  • add or subtract a 2-digit number mentally, using a nearby tens number;
  • work backwards through a story to find how many there were at first.
1

Step 1

Adding 4-digit numbers with renaming

Start with the ones. Line up the ones under the ones, then add one column at a time: ones, tens, hundreds, thousands. When a column makes 10 or more, write its ones digit and rename the 1 into the next column, where it is added too.

Tap Next column

ThHTO26483725+
Visitors: 2648 + 3725. Line up the ones under the ones. Tap Next column to start with the ones.
Try it

Find 3478 + 1856.

▶ Watch the lesson: Adding four digitsPractise 7 questions →
2

Step 2

Subtracting across zeros

Rename from the next place that has something. Put the greater number on top and start with the ones. If a column has too few, rename 1 from the place on its left. If that place is 0, keep going left, and every 0 you pass becomes 9.

Tap Next column

ThHTO70421625−
7042 minus 1625. The greater number goes on top, ones under ones. Tap Next column to start with the ones.
Try it

Find 6005 − 2738.

▶ Watch the lesson: Subtract and regroupPractise 7 questions →
3

Step 3

Mental addition and subtraction

Use a tens number close by, then adjust. To add 29, add 30 instead, then minus the extra 1. To minus 39, minus 40 instead, then add the extra 1 back. The orange jump on the number line is that extra.

Tap Next jump

58 + 29 = ?
58
58 + 29. 29 is close to 30, and 30 is easy to add. Tap Next jump.
Try it

To work out 46 + 39 in your head, you add 40. What do you do next?

▶ Watch the lesson: Mental add and subtractPractise 7 questions →
4

Step 4

How many at first word problems

Undo the last change first. When a story gives the amount at the end, work backwards from the last change. Something received is undone by subtracting it. Something given out is undone by adding it back. Then run the story forwards to check.

Tap Undo

A library had some brochures. First, it gave out 125. Last, it received 48. It had 376 at the end. How many brochures did it have at first?

At first
?
↓ gave out 125
After giving out
?
↓ received 48
At the end
376
We know how many it had at the end: 376. Work backwards from the last change. Tap Undo the last change.
Try it

A shop had some pens. It sold 230 pens. Then it received 145 pens. It has 600 pens now. How many pens did it have at first?

▶ Watch the lesson: Totals and starting amountsPractise 6 questions →Practise 12 mixed questions →

Primary 3 addition and subtraction questions, worked step by stepCover the working and try each one first. Open the hint if you are stuck, then reveal the lines one by one.

Add in columnsBasic

A library has 3586 storybooks and 2947 comics. How many books does it have altogether?

Line up the ones under the ones and start with the ones. Rename whenever a column makes 10 or more.
  1. Ones: 6 + 7 = 13. Write 3 and rename 1 ten into the tens.
  2. Tens: 8 + 4 + 1 = 13. Write 3 and rename 1 hundred into the hundreds.
  3. Hundreds: 5 + 9 + 1 = 15. Write 5 and rename 1 thousand into the thousands.
  4. Thousands: 3 + 2 + 1 = 6. So 3586 + 2947 = 6533.
Answer: 6533 books
Across zerosBasic

Find the value of 6000 − 2475.

The ones, tens and hundreds of 6000 are all 0. Rename from the thousands, across the zeros.
  1. Rename 1 thousand as 10 hundreds, 1 hundred as 10 tens and 1 ten as 10 ones: 5 thousands, 9 hundreds, 9 tens, 10 ones.
  2. Ones: 10 minus 5 is 5. Tens: 9 minus 7 is 2.
  3. Hundreds: 9 minus 4 is 5. Thousands: 5 minus 2 is 3.
  4. 6000 minus 2475 = 3525. Check: 3525 + 2475 = 6000.
Answer: 3525
Mental mathsIntermediate

Work out 93 − 47 mentally.

47 is close to 50. Minus 50, then think about what to do with the extra.
  1. 47 is 3 less than 50, so minus 50 instead: 93 minus 50 = 43.
  2. We only needed to minus 47, so we subtracted 3 too many.
  3. Add the 3 back: 43 + 3 = 46.
Answer: 46
TotalsIntermediate

A stall sold 1468 curry puffs on Saturday. On Sunday, it sold 395 more curry puffs than on Saturday. How many curry puffs did it sell on the two days altogether?

First find how many it sold on Sunday. Then add the two days.
  1. Sunday: 1468 + 395. Ones 8 + 5 = 13, write 3. Tens 6 + 9 + 1 = 16, write 6. Hundreds 4 + 3 + 1 = 8.
  2. So it sold 1863 curry puffs on Sunday.
  3. Both days: 1468 + 1863. Ones 8 + 3 = 11, write 1. Tens 6 + 6 + 1 = 13, write 3. Hundreds 4 + 8 + 1 = 13, write 3. Thousands 1 + 1 + 1 = 3.
  4. Altogether: 3331 curry puffs.
Answer: 3331 curry puffs
Work backwardsChallenge

A hall had some chairs. First, 286 chairs were moved out to the garden. Then 1540 chairs were delivered. In the end, there were 4105 chairs in the hall. How many chairs were in the hall at first?

Start from the 4105 at the end. Undo the delivery first, then undo the chairs moved out.
  1. Undo the last change. 1540 chairs were delivered, so subtract them: 4105 minus 1540.
  2. Ones 5 minus 0 is 5. Tens: rename 1 hundred, 10 minus 4 is 6. Hundreds: rename 1 thousand, 11 minus 5 is 6. Thousands 3 minus 1 is 2. Before the delivery: 2565.
  3. Undo the first change. 286 chairs were moved out, so add them back: 2565 + 286 = 2851.
  4. Check forwards: 2851 minus 286 = 2565, and 2565 + 1540 = 4105.
Answer: 2851 chairs
5

Step 5

Check yourself

Five questions, one for each skill in this chapter. Tap an answer to see why, then follow the link to the set that fits.

1. Find 4567 + 2385.

2. Find 4003 − 1658.

3. What is 72 − 38?

4. Ravi had some stickers. He gave away 45 stickers. Then he bought 120 more. He has 310 stickers now. How many stickers did he have at first?

5. A school has 2350 pupils. 1186 of them are girls and the rest are boys. How many more girls than boys are there?

0/5
Answer all five to see where to practise next.
For parents

Let your child say each column aloud. Before each tap of Next column, ask for the line first, such as "8 plus 5 is 13 ones, so 1 ten goes on top." In subtraction, ask which place the renaming comes from before the screen shows it.

For mental sums, ask how far the easy tens number is from the real one, and which way to put it right. For story problems, ask your child to name the last change before any working. Try the worked examples on paper and reveal one line at a time to compare.

More study guides

Before this: Numbers up to 10 000Next: MoneyPrimary 3 Multiplication and Division study guidePrimary 3 More Word Problems study guidePrimary 4 Four Operations of Whole Numbers study guidePrimary 5 Four Operations of Whole Numbers
Lessons and practice

P3 Addition and Subtraction Within 10 000 lessons and practice

4 lesson videos and 39 questions across four subtopics, from Basic to Challenge, each with a worked solution.

Watch and practise →