Work through the levels in order. Type your answer and press Check — open the worked solution if you get stuck. Answers like -6, 3/4 or 0.25 are typed exactly as shown. A ⭐ Bonus Challenge at the end is extra credit — skip it if the rest was hard work.
Level 1 · Warm-up
1 List every factor of 20. (separate them with commas, smallest first)
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1 × 20, 2 × 10 and 4 × 5, so the factors are 1, 2, 4, 5, 10, 20.
2 Is 17 prime or composite?
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Nothing divides 17 except 1 and 17, so it has exactly two factors — it is prime.
3 Is 1 prime, composite, or neither?
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1 has only one factor, so it is neither prime nor composite.
Level 2 · Core
4 List all the prime numbers between 30 and 40. (separate them with commas)
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31 and 37. The other odd ones fail: 33 = 3 × 11, 35 = 5 × 7 and 39 = 3 × 13.
5 Does 234 divide by 9?
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2 + 3 + 4 = 9, a multiple of 9, so yes — 234 = 9 × 26.
6 How many factors does 36 have? (give just the count)
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The factors are 1, 2, 3, 4, 6, 9, 12, 18 and 36 — 9 of them. The pair 6 × 6 adds only one new number.
Level 3 · Challenge
7 Is 91 prime?
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No — 91 = 7 × 13, so it has four factors and is composite.
8 What is the smallest prime number greater than 50?
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51 = 3 × 17 and 52 is even, so the smallest prime above 50 is 53.
9 Ana says 57 must be prime because it is odd and does not end in 5. Is she right?
Show worked solution
No. 5 + 7 = 12, a multiple of 3, so 57 = 3 × 19 — composite.