Multiples, Factors & Primes

Multiples, Factors & Primes

1. A prime number is a number greater than 1 which has only two factors: Itself & 1.

   • Prime numbers to 100: 2,3,5,7,11,13,17,19, 23,29,31,37,41,43,47, 53,59,61,67,71,73,79, 83,89,97
     • The sum of two prime numbers can be a prime number but only when one of the prime numbers is 2
       • 2+3=5 2+5=7 2+11=13
     • A number written as the product of prime numbers is written in prime factor form
       • 720 = 2 x 2 x 2 x 2 x 3 x 3 x 5 as prime factor form is 720 = 2(4) x 3(2) x 5 (brackets are to the power of)
         • 2, 3, and 5 are prime factors of 720

2. Multiples of a number are the results of multiplying the number by a positive whole number.

   • 15=3x5 308=4x7x11
     • 15 is a multiple of 3 & also of 5
     • 3 is a factor of 15. 5 is also a factor
     • 308 is a multiple of 4, 7 & 11
     • 4, 7 & 11 are factors of 308
     • The factors of a number are whole numbers that divide exactly into the number. The factor includes 1 & itself.