Classify Prime, Composite, and One

Supplied materials

• Paper and a pencil; drawing and spoken explanations are welcome. An adult may read directions and options aloud.
• Supplied worked-case record: Thirteen has factors one and thirteen only, so it is prime.
• All quantities and shape descriptions are supplied in the worked example and questions; no purchase or personal information is needed.

Learn the idea

A prime whole number is greater than one and has exactly two positive factors: one and itself. A composite has more than two positive factors. One is neither prime nor composite because it has only one positive factor. Testing factor pairs supports the classification.

List the target’s positive factor pairs or identify a nontrivial pair. Classify as prime when only one and itself divide it, composite when another factor exists, and neither when the target is one.

A single nontrivial factor pair proves a number is composite. One is neither prime nor composite. Record positive factors and count how many different factors there are.

1. Record positive factors and count how many different factors there are.
2. Follow the worked example. Point to each number or shape feature and say what it tells you.
3. List the target’s positive factor pairs or identify a nontrivial pair.
4. Try the question and then the three practice questions. Check your answers and explain any change you make.

Check your reasoning

Your answer is temporary and is not saved to an account. Download your current answer before leaving or reloading. Written work on paper or in another app stays in your own file.

Take it further

Classify 19 and 27. Expected: prime and composite, with 3×9 supporting 27.

Nothing here is saved to an account or sent to a teacher. The answer download includes your current choice and any checked feedback. It does not include choices from the separate More practice section. Download that section separately.