Subtraction Word Problems Up to 100

A subtraction word problem tells a short story about two amounts, where numbers between 0 and 100 are used, and asks you to find how many are left, how much less one amount is, or how far apart two amounts are. Instead of just seeing a subtraction sentence like \( 84 - 27 \), you have to read the story, figure out what is being asked, and turn it into a number sentence yourself before solving it.

These problems build on basic subtraction skills, so it helps to already feel comfortable with subtraction facts up to 100 before working through word problems.

1. Read the problem carefully, maybe more than once, to understand the situation.
2. Identify the total or starting amount, and the amount being removed or compared.
3. Look for key words that hint at subtraction.
4. Write a number sentence in the form \( a - b = c \).
5. Solve the subtraction, regrouping tens and ones if needed.
6. Check that the answer makes sense with the story, and label it with the correct units.

Certain words in a story almost always point to subtraction. Watch for phrases like:

• left, left over, remaining
• fewer, less than
• how many more (to find a difference)
• difference between
• gave away, used, sold, ate, lost

Spotting these words is the fastest way to decide whether a problem needs subtraction rather than addition.

Maria had 63 stickers. She gave 28 of them to her friends. How many stickers does Maria have left?

The word "left" signals subtraction. The starting amount is 63, and the amount taken away is 28, so the number sentence is \( 63 - 28 = c \). Since 3 ones is less than 8 ones, regroup a ten, so 63 becomes 5 tens and 13 ones: \( 13 - 8 = 5 \) ones and \( 5 - 2 = 3 \) tens. So \( 63 - 28 = 35 \). Maria has 35 stickers left.

A parking lot has 92 cars. Another lot has 47 cars. How many more cars are in the first lot?

The phrase "how many more" tells us to find the difference between the two amounts: \( 92 - 47 = c \). Since 2 ones is less than 7 ones, regroup a ten again: \( 12 - 7 = 5 \) ones and \( 8 - 4 = 4 \) tens, giving \( 92 - 47 = 45 \). The first lot has 45 more cars than the second lot.

Once a word problem is turned into a number sentence, you can solve it with whichever strategy feels most reliable. Some students prefer using number lines to subtract up to 100, jumping back by tens and then ones. Others like breaking numbers apart with place value, similar to the method used in subtracting with digits up to 100. Both approaches lead to the same correct answer, so use the one that makes the most sense to you.

After solving, add the difference back to the number you subtracted. If \( 63 - 28 = 35 \), then \( 35 + 28 \) should equal 63. This quick check catches regrouping mistakes and confirms the story makes sense.

• Underline the total or starting number in one color and the amount removed in another.
• Draw a quick bar model or number line before writing the number sentence.
• Ask whether the problem is asking for "how many left" or "how many more" (a comparison), since both use subtraction but describe the story differently.
• Estimate first by rounding to the nearest ten, then check that your exact answer is close to the estimate.

Related lessons

• Math 2