Ch. 4, Sec 1: Divisability and Factors

Chapter 4: Section 1: Divisibility and Factors By Ms. Dewey-Hoffman December 1 st , 2009

Warm Ups for Chapter 4
Find the Quotient: 147  3 =
Find the Quotient: 273/3 =
Find the Quotient: 450/10 =
Find the Product: 4 • 4 • 4 =
Find the Product: (-2)(-2)(-2) =
Find the Product: (10)(10)(10)(10) =

Warm Ups for Chapter 4
Write TWO numbers, that when multiplied together, give this product:
12
50
36
24

Section 4.1: Divisibility and Factors
One integer is DIVISIBLE by another if the remainder is 0 when you divide.
Divisibility Rules for 2, 5, and 10 .
An integer is divisible by…
2, if it ends in 0, 2, 4, 6, and 8 .
5, if it ends in 0 or 5 .
10, if it ends in 0 .

Examples: Divisibility Rules
Is the first number divisible by the second?
567 and 2?
1,015 and 5?
111,120 and 10?
53 and 2?
1,118 and 2?

Divisibility Rule for 3 and 9.
See if you can pick out the pattern…
Yes Yes Yes Yes 1 + 0 + 1 + 7 = 9 1,017 No No No No 2 + 1 + 5 = 8 215 Yes Yes Yes Yes 4 + 6 + 8 = 18 468 No Yes No Yes 2 + 8 + 2 = 12 282 Is the Number Divisible by: 3? 9? Is the Sum Divisible by: 3? 9? Sum of Digits Number

Divisibility Rule for 3 and 9.
From the pattern we saw before…
An integer is divisible by…
3, if the sum of its digits is divisible by 3 .
9, if the sum of its digits is divisible by 9 .

Example Problems:
Is the first number divisible by the second? Explain.
64 by 9?
472 by 3?
174 by 3?
43,542 by 9?

Finding Factors
One integer is a FACTOR of another integer if it divides that integer with remainder zero.
number number number

Finding Factors
So find all the different combinations of factors
12?
16?
18?
24?
1(12), 2(6), 3(4): so, 1, 2, 3, 4, 6, and 12 1(16), 2(8), 4(4): so, 1, 2, 4, 8, and 16 1(18), 2(9), 3(6): so, 1, 2, 3, 6, 9, and 18 1(24), 2(12), 3(8), 4(6): so, 1, 2, 3, 4, 6, 8, 12, and 24

Word Problem:
There are 20 choral students singing at a school concert. Each row of singers much have the same number of students. If there are at least 5 students in each row, what are all the possible arrangements?

List the positive factors of each number.
10
21
31
1, 2, 5, 10 1, 3, 7, 21 1, 31

Homework #40
USE YOUR NOTES TO REMIND YOU OF THE DIVISIBILITY RULES!!!
Page 174: 6-35 all.

Ch. 4, Sec 1: Divisability and Factors

by Middle School on Dec 01, 2009

Accessibility

Categories

Tags

Upload Details

Usage Rights

1 Embed 3

Statistics

Ch. 4, Sec 1: Divisability and Factors — Presentation Transcript