Primes

• A prime number has only two factors: 1 and itself.
• 51, 57, 87, and 91 are not prime numbers.
• Two (2) is the only even prime number.
• Numbers are relatively prime if they have no common factors other than (one) 1, that is, their Greatest Common Factor (GCF) is 1.

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  Browse Math Tutoring Tips:

• Introduction
• Wholes and Parts
• Zero - 0
• One - 1
• Fractions
• Common Fractions and Equivalences
• Useful Squares
• Factors of 100
• Useful Multiples of 15 and 16
• Percents
• Primes
• Geometry
• Language of Math
• Other Useful Information
• Number systems
• A Different Way to Think about Percent
• Conclusion

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