Prime numbers

Primes have exactly two factors; composite numbers have more. Read one part at a time and tap “I know this”. Then test yourself in the quiz.

Your progress0 of 1

A prime number has exactly two factors: 1 and itself. A composite number has more than two factors.

Primes up to 50: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47.

Watch out

1 is not prime (only one factor). 2 is the only even prime.

Tap when you could tell someone without looking.

Remember this and test yourself

Remember this: your summary

Write these points in your book. Read them again the night before the test.

Memory trick

Prime = private: only 1 and itself are invited.

Flash cards · Tap to turn over

First say the answer yourself, then turn the card over.

Test yourself · Part 2

Read the question and the answer. Is the answer right? Tap True or False.

Now the real quiz!

The quiz has many more questions on this topic. Every question shows straight away whether you are right and explains why.

For parents

Let your child work the examples on paper and explain them to you.
The ticks (“I know this”) are saved on this device only. We never ask for names or emails.

Follows CAPS for Grade 5 Mathematics. Always check your teacher’s notes and textbook too.