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Whole Numbers and Primes
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Whole Numbers and Primes
📚 Part 1: Understanding Whole Numbers and Primes
1. What are whole numbers? Write your definition below:
2. Circle all the whole numbers from this list:
-3, 0, 2.5, 7, 15, -8, 100, 3/4, 42, 0.25
3. A prime number is a whole number greater than 1 that has exactly _____ factors.
one
two
three
four
4. Which of these numbers are prime? Check all that apply:
2
9
11
15
17
21
🔍 Part 2: Prime and Composite Numbers
5. Complete the table by writing "Prime" or "Composite" for each number:
13: ____________
20: ____________
23: ____________
28: ____________
29: ____________
6. Use the Sieve of Eratosthenes method to find all prime numbers from 2 to 30. Cross out the composite numbers and circle the primes:
2 3 4 5 6 7 8 9 10
11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29 30
7. List all the prime numbers you found from 2 to 30:
🌟 Part 3: Real-World Application
8. Prime numbers are used in computer security and internet banking to keep information safe. Why do you think prime numbers are useful for creating secret codes? Explain your thinking:
9. Challenge: Find the smallest prime number greater than 50. Show your working:
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