Page 24 - NUMINO TG_6A

01What Do We Have in Common? Unit

CMath Vo abulary prime factorization: writing a composite number as the product of all of its factors that are prime

numbers

Method 2 Use a ladder diagram. Method 2: Find the least common multiple of
Find the least common multiple of 12 and 30. 12 and 30 using a ladder diagram.

Use a ladder diagram to divide the numbers using common factors. Determine a common factor of 12 and 30.
Divide the two numbers by the common
A common factor of 12 and 30 2 12 30 factor and write the new numbers below.
A common factor of 6 and 15 3 6 15 2 12 30
25
Find the least common multiple. 6 15
Determine if there is a second common
2 12 30 2ß ß3ß ß2ß ß5ß=ß60 factor.
3 6 15 Divide the numbers by the second
common factor and write the numbers
25 below.
3 6 15
The LCM: 60
25
2 . Find the least common multiple of the two numbers using the method Repeat this process until there are no
common factors, then multiply all of the
above. numbers on the outside of the ladder.

a. 2 12 24 b . 3 36 45 2. Have students determine the least
common multiple using method 2.
6 6 12 3 12 15

12 45

The LCM: 2 6 1 2 = 24 The LCM: 3 3 4 5 = 180

c . 8 56 72 d . 7 70 63

79 10 9

The LCM: 8 7 9 = 504 The LCM: 7 10 9 = 630

1. What Do We Have in Common? 5

Finding All the Prime Factors

Example: What is the least common multiple of 665 and 285?

Remove the obvious prime factors first

665 5 133, 285 5 57

If you are stumped on finding the second prime factors, approximate the square root of the number.

√133 12

Divide the number by all of the numbers up to the square root.

133 2 66 1 , 133 3 44 1 , 133 4 33 1 , 133 5 26 3 , 133 6 22 1 , 133 7 19
2 3 4 5 6

6A Unit 01 007