Compare lengths
When you have two things, you often ask "which is longer?" or "by how much do they differ?".
To answer that, you have to measure them first.
Which is longer — compare numbers
How to do it:
- Measure the first thing.
- Measure the second.
- Compare the numbers.
Example: Pen A = 14 cm, Pen B = 18 cm.
14 < 18 → Pen B is longer.
By how much — subtract
We often want the difference:
Longer − shorter = difference.
For Pen A (14 cm) and Pen B (18 cm):
Pen B is 4 cm longer.18 − 14 = 4.
Example with the same unit
Ribbon A = 50 cm, ribbon B = 75 cm.
75 − 50 = 25 cm.
Ribbon B is 25 cm longer.
Watch out: same unit
When comparing, both things must be in the same unit!
Pen = 15 cm. Table = 1 m.
I cannot compare 15 and 1 — that would be wrong.
First convert: 1 m = 100 cm.100 − 15 = 85 cm.
The table is 85 cm longer than the pen.
Trick: line them up
If you don't have a ruler, you can compare lengths physically:
- Put the starts of the things on the same line.
- See which one sticks out further.
For pencils, for example: line them up at the points and see which one is longer.
Summary
- Longer / shorter = compare the numbers.
- By how much they differ = longer − shorter.
- Before comparing, both must be in the same unit.
- Quick comparison: line up the starts side by side.