Measurement & Data

Length Word Problems

Using addition and subtraction to solve length word problems.

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

Prerequisites

Measuring in Standard Units

Solving Problems About Length

Once length is measured in a standard unit, length word problems work exactly like any other addition or subtraction word problem — the numbers just happen to represent inches, feet, centimeters, or meters instead of a plain count of objects.

Worked Example — Adding Two Lengths

A ribbon is cut into two pieces: one piece is 14 centimeters long, and the other is 9 centimeters long. What was the length of the ribbon before it was cut? The two pieces join back together to make the whole ribbon, so add: 14 + 9 = 23. The ribbon was 23 centimeters long.

Worked Example — Finding a Difference in Length

One rope is 32 feet long, and another rope is 18 feet long. How much longer is the first rope than the second? This compares two lengths, so subtract: 32 − 18 = 14. The first rope is 14 feet longer than the second.

Worked Example — Finding a Missing Length

A board is 6 feet long. A carpenter cuts off a piece and 2 feet remain. How long was the piece that was cut off? The whole board splits into the cut piece and the 2 feet that remain, so subtract: 6 − 2 = 4. The cut piece was 4 feet long.

Tip

Draw a simple bar or line showing the whole length and its parts — it makes it much easier to see whether a problem is asking to add two parts or find a missing part.

Common Mistakes

Losing track of which unit the problem is using and mixing feet with inches in the same calculation.
Check the unit stated in the problem and keep every number in that same unit throughout the whole calculation.
Subtracting in the wrong order when comparing two lengths, giving a negative or backward result.
When finding how much longer one length is than another, always subtract the shorter length from the longer length.

Key Takeaways

Length word problems use the same addition and subtraction thinking as any other word problem.
A whole length can be split into parts, and any missing part can be found using addition or subtraction.
Drawing a simple diagram of the whole length and its parts helps decide which operation to use.

Summary

Length word problems apply addition and subtraction to real measured distances. The next topic shifts from measuring space to measuring time and money, starting with reading a clock more precisely.

Track your progress

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