Adding and subtracting large numbers: what children learn
In this game children work out additions and subtractions with five- and six-digit numbers. The method is the same as for smaller numbers; the challenge is keeping every digit in the right column.
Supports part of Common Core 4.NBT.B.4: the standard algorithm with multi-digit whole numbers, here up to six digits. This focused game does not cover the entire standard.
Common Core connection: 4.NBT.B.4. This is focused practice for part of the standard.
How to play
Answer 10 questions before the clock runs out. Tap an answer, or press 1 to 4. Each game has 10 multiple-choice questions and a 180-second timer. A wrong answer shows the correct one before moving on. You earn up to three stars depending on your score.
Step by step
- Line up from the ones. Write the numbers so that ones, tens, hundreds and so on are in columns.
- Work right to left. Carry or exchange as you go, just as with smaller numbers.
- Use the commas. The comma separates thousands. It helps you line up the digits.
- Estimate to check. Round each number and check that your answer is close.
Worked examples
Example 1: 70,711 + 44,496
Working: Estimate: 71,000 + 44,000 = 115,000. Add in columns from the ones.
Answer: 115,207
Example 2: 693,299 − 66,540
Working: Estimate: 693,000 − 67,000 = 626,000. Subtract in columns from the ones.
Answer: 626,759
Example 3: 842,634 − 55,642
Working: Estimate: 843,000 − 56,000 = 787,000. Subtract in columns from the ones.
Answer: 786,992
Common mistakes and how to fix them
- Lining up a five-digit number under a six-digit number from the left. Line up from the ones. Use squared paper.
- Missing an exchange in a long subtraction. Check each column before moving on.
- Not checking with an estimate. Round to the nearest thousand and compare.
Activities to try at home
- Add the populations of two towns or cities.
- Find the difference between two car mileages.
- Check large calculations with a calculator after doing them on paper.
Ideas for the classroom
- Students estimate first and only calculate exactly when the estimate is in a given range.
- Give calculations with deliberate errors for students to find.
- Use real data, such as stadium capacities, for word problems.
Free printable game and worksheet
The free printable starts with a game sheet, such as a color-by-answer picture, an answer maze or a secret-code joke, followed by a worksheet. Both use the same checked questions as the online game, and the answers are on the last page. Print it, or save it as a PDF from your browser’s print menu.
Open the free printable game and worksheet
Frequently asked questions
How should I choose this game for my learner?
Supports part of Common Core 4.NBT.B.4: the standard algorithm with multi-digit whole numbers, here up to six digits. This focused game does not cover the entire standard.
When should children use a mental method instead?
When the numbers are round or close to round, such as 45,000 − 2,000.
Can it be played with a keyboard?
Yes. Press 1, 2, 3 or 4 to choose an answer.