Addition & subtraction
Addition and Subtraction Word Problems
Year 1 · Year 2
- ✓By the end of this lesson students will be able to solve one-step addition and subtraction word problems.
- ✓By the end of this lesson students will be able to identify key words that indicate addition or subtraction.
- ✓By the end of this lesson students will be able to write number sentences to represent word problems.
- ✓By the end of this lesson students will be able to solve simple missing number problems related to addition and subtraction.
Key concepts
A word problem is like a short story that has numbers in it. It asks you a question that you need to answer using your maths skills, either by adding or subtracting. You need to read the story carefully to understand what it is asking you to do.
In addition word problems, you usually need to find a total or how many things there are altogether. Look for words like 'altogether', 'total', 'in all', 'add', 'plus', 'more than', or 'combine'. These words are clues that you need to add the numbers together.
In subtraction word problems, you usually need to find out how many are left, the difference between two numbers, or how many fewer there are. Look for words like 'left', 'take away', 'minus', 'fewer', 'difference', 'how many more', or 'remove'. These words are clues that you need to subtract one number from another.
Sometimes, a number sentence will have a number missing, like 3 + ? = 5 or 7 - ? = 2. These are called missing number problems. Your job is to work out what number should go in the empty box or where the question mark is to make the number sentence correct.
Key facts to remember
- 1Always read the word problem carefully, sometimes more than once.
- 2Look for the numbers in the problem.
- 3Look for special 'key words' that tell you if you need to add or subtract.
- 4'Altogether', 'total', 'in all', 'plus' usually mean you need to ADD.
- 5'Left', 'take away', 'minus', 'fewer', 'difference' usually mean you need to SUBTRACT.
- 6You can use your fingers, counters, or draw pictures to help you solve problems.
- 7Always write down the number sentence (e.g., 5 + 3 = 8) to show your working.
- 8Check your answer to make sure it makes sense in the story.
Worked examples
Example 1
There are 5 red cars and 3 blue cars in the car park. How many cars are there altogether?
Answer
There are 8 cars altogether.
You can draw pictures of the cars to help you count them!
Example 2
A baker made 9 cakes. He sold 4 of them. How many cakes does the baker have left?
Answer
The baker has 5 cakes left.
You can use counters or draw circles and cross out the ones that were sold.
Example 3
Sam had some stickers. He was given 2 more stickers and now he has 6 stickers. How many stickers did Sam have to start with?
Answer
Sam had 4 stickers to start with.
Using a number line can help you jump forwards or backwards to find the missing number.
Common mistakes
- ✗Not reading the problem carefully and missing important information.
- ✗Choosing the wrong operation (adding when you should subtract, or subtracting when you should add).
- ✗Making simple counting errors when adding or subtracting.
- ✗Not writing down the number sentence before trying to find the answer.
- ✗Giving just a number as an answer without saying what it means (e.g., '8' instead of '8 cars').
Exam tips
- ★Underline or circle the important numbers and keywords in the problem to help you focus.
- ★Draw a simple picture or use objects to help you understand what is happening in the problem.
- ★Always write the number sentence you are using to solve the problem clearly.
- ★Check your answer by doing the calculation again, or by using a different method if you can.
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