1. SWBAT to use divisibility rules for 2, 3, 4, 5, 6, 8, 9, and 10

2. What is divisibility? Divisibility
If a number goes into another number, without a remainder
351 is divisible by 9
9 goes into 351, 39 times with no remainder

3. Divisibility Rules 2 3 4 5 6 8 9 10
it is an even number (ends in 0, 2, 4, 6, 8)
the sum of its digits is divisible by 3
the last two digits form a number divisible by 4
it ends in a 0 or a 5
it is divisible by both 2 and 3
the last three digits form a number divisible by 8
the sum of its digits is divisible by 9
it ends in a 0

4. Examples
333
128
7,535
8,289
99,483
67,704
3,95_, by 10
17,84_, by 3
17,39_, by 5
27,1_8, by 6
37,6_3, by 9

5. Try These
128
2, 4, 8
9410
2, 5, 10
17,934
2, 3, 6
270,228
2, 3, 4, 6
243,05__; by 9 4
13,__12; by 8 and by 3 5
20,71___; by 4
2 or 6

6. Prime and Composite Numbers
SWBAT identify prime and composite numbers

7. Definitions Prime number Composite number
A whole number greater than 1 that has exactly two factors, itself and 1
Composite number
A whole number greater than 1 that has more than two factors
The numbers 0 and 1 are neither prime nor composite.

8. Examples Tell whether each number is prime, composite, or neither 2435 2 9 19 21 1
10,011

9. Try These 81 41 51 37,311 neither Composite, divisible by 9 Prime
neither 81
Composite, divisible by 9 41
Prime 51
Composite, divisible by 3
37,311

10. Perfect Numbers
A perfect number is the sum of all its factors, not including itself.
6 has factors of 1, 2, 3, and 6
If you add (all the factors, except for itself), you get 6
A perfect number?