# Math CH-2

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1. Prime Numbers
• only 1 and itself are the factors.
• hint:2,3,5,7,11,13,17,19,23,29,31,37,41

exp. 11x1=11 or 13x1=13
2. List all factors of #24
or
Find all factors of 24
• exp: 1x24 answer:1,2,3,4,6,8,12,24
• 2x12 are all factors of 24
• 3x8
• 4x6
3. COMPOSITE NUMBER
• has more than 2 factors.
• hint: 4,6,8,9,10,12,14...

exp:2x2=4 or 5x2=10
4. Divisible by 2
if its last digit is 0,2,4,6,8

exp: 244 yes because its a 4
5. Divisible by 3
• if the sum of all of its digits can be ÷ by 3.
• exp: 333 =9 yes because it equals to 9
6. Divisible by 4
• if its las two digits can be ÷ by 4
• exp:644 =44 yes because its 44
• (not sum)
7. Divisible by 5
• if its last digit is a 0 or 5
• exp. 025 yes because its a 5
8. Divisible by 6
• if the sum of its digits is an even number and can be ÷ by 3.
• hint:2,4,6,8,10...
• exp:576=18 yes because 18 is even and is ÷ by 3
9. Divisible by 8
• if its last 3 digits can be ÷ by 8.
• exp:5,088 =88 yes because it can be ÷ 8
10. Divisible by 9
• if the sum of all digits can be ÷ by 9.
• exp: 207=9 yes becaus it can ÷ by 9
11. Divisible by 10.
• only if its last digits is a 0
• exp: 240 yes its a 0 at the end
12. Find the prime factorization of 36
• do the factorization tree and find primes.
• exp:36
• is 2.3.2.3
13. Finding the Greatest Common Factor (GCF):
exp:18 and 24
• find the ones that are same and (x)multiply.
• exp 18=2.3.3 =2.3=6
• 24=2.2.2.2.3 =2.3=6
• so the answer is 6
14. Equivalent fractors
• 1. 4 7x4=28 cross multiply
• 7 28 1x28=28 EQUIVALENT
15. Simplyfi (write in lowest term) "reduce"
• 6 =2x3 =3 cross out same and multiply
• 8 2x2x2 =4
16. Multiply fractions
multiply them horizontaly and find the prime factorizations and cross out same and multiply the ones that remain.
17. Dividing franctions
we change the reciprocals then we multiply and follow multiply directions
18. how to simply one fraction.
just find the prime factorization and cross out same and the answer is whats left.
19. finding the GCF of fractions
• find the common ones and multiply them.
• 56=2x2x2x7=8
• 78=2x2x2x3x3=8

so 8 is the GCF of 56 and 78
20. Mixed numbers
• exp 5 1/3
• we multiply 5 and 3 demoninator and + 1 and keep the 3 since is the demominator

### Card Set Information

 Author: igarcia280 ID: 71530 Filename: Math CH-2 Updated: 2011-03-09 07:07:15 Tags: math Folders: Description: math ch 2 review Show Answers:

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