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Prime Factorization Tricks!. 1. ALL NUMBERS HAVE 1 AS A FACTOR!. 2. Even numbers! Numbers ending in 0, 2, 4, 6, 8 Example: 1092843972 __________2 = even number 2 is a factor!. 3. When you add up the digits, the number is divisible by 3 Example: 489 4+8+9=21 21/3=7
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1 • ALL NUMBERS HAVE 1 AS A FACTOR!
2 • Even numbers! • Numbers ending in 0, 2, 4, 6, 8 • Example: • 1092843972 • __________2 = even number • 2 is a factor!
3 • When you add up the digits, the number is divisible by 3 • Example: • 489 • 4+8+9=21 • 21/3=7 • Therefore 3 is a factor of 489
4 • If the last 2 digits are divisible by 4, then the whole number is! • Example: • 344 • _44/4 =11 • 344 has 4 as a factor!
5 • Always ends in 0 or 5 • Example: • 928420 • _____0 • This number has 5 as a factor!
6 • If you already know the number has the factors 3 and 2, then it also has 6! • Example: • 336 • __6= even number; 2 is a factor! • 3+3+6=12 12/3=4; 3 is a factor! • If 2 and 3 are factors, 6 is a factor!
7 • No special rule for 7s • I guess you guys will just have to study them harder…
8 • If the last 3 numbers are divisible by 8, then 8 is a factor! • Example: • 7168 • _168/8=_21 • This has a factor of 8!
9 • When you add up the digits, the number is divisible by 9! • Example: • 288 • 2+8+8=18 • 18/9=2 • This number has a factor of 9!
10 • Number that end in 0! • Example: • 29832740 • _______0 • This number has a factor of 10!
