Operations & Algebraic Thinking

One-Step Word Problems Within 100

Using addition and subtraction to solve word problems within 100.

Foundational15 min lesson2 min readUpdated August 12, 2026Author not yet attributed

Word Problems with Bigger Numbers

In Grade 1, you solved addition and subtraction word problems with numbers up to 20. The same thinking works for larger numbers too — the only thing that's changed is the size of the numbers in the story.

Just like before, look for what's happening in the story. Groups joining together or growing point to addition. Groups shrinking, having part removed, or being compared point to subtraction. The numbers being bigger doesn't change which operation the story calls for.

Worked Example — An Addition Story Within 100

A school has 34 students in one classroom and 28 students in another. How many students are there in all? The two groups are being combined, so add: 34 + 28 = 62. There are 62 students in all.

Worked Example — A Subtraction Story Within 100

A parking lot has 76 cars. By the end of the day, 39 cars have driven away. How many cars are left? Cars are leaving the group, so subtract: 76 − 39 = 37. There are 37 cars left.

Tip

For larger numbers, sketching a quick picture of tens and ones — or writing the numbers stacked by place value — makes it easier to add or subtract accurately without losing track of a digit.

Common Mistakes

Adding or subtracting the digits without lining them up by place value, mixing tens with ones.
Stack the numbers so the ones digits line up under each other and the tens digits line up under each other before adding or subtracting.
Choosing the operation based on which number is bigger instead of what the story describes.
Let the action in the story — joining or leaving — decide the operation, the same way it did with smaller numbers in Grade 1.

Key Takeaways

Word problems within 100 use the same addition and subtraction thinking as smaller numbers.
The story's action decides whether to add or subtract, no matter how large the numbers are.
Lining numbers up by place value helps avoid mistakes with bigger numbers.

Summary

One-step word problems within 100 apply familiar addition and subtraction thinking to larger numbers. The next lesson builds on this by chaining two operations together in a single problem.

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