Least common multiple

Find to find and when to use Least Common Multiple

1. Least Common Multiple Finding the Least of the Most Melanie Anderson

2. Least Common Multiple A Multiple of a number is the product of the number and any whole number. Example: number x number = product (multiple) When you count by twos, fives or tens, you are using multiples . 2: 2, 4, 6, 8, 10, 12 multiples of two 4: 4, 8, 12, 16, 20 multiples of four 5: 5, 10, 15, 20, 25 multiples of five

3. Least Common Multiple Multiples of 6 1 x 6 = 6 2 x 6 = 12 3 x 6 = 18 4 x 6 = 24 5 x 6 = 30 6 x 6 = 36 7 x 6 = 42 Multiples of 7 1 x 7 = 7 2 x 7 = 14 3 x 7 = 21 4 x 7 = 28 5 x 7 = 35 6 x 7 = 42 The answer or product is the multiple . To help you find the LCM make a list of the multiples of the number then draw circle around the number that is the same. 42 is the lowest number that is the same in both list, 42 is the LCM

4. The Least Common Multiple or the LCM is the lowest number you get when you compare the multiples of numbers. Ex. 1: Find the LCM of 10 and 30 10: 10, 20, 30 , 40, 50 30: 30 , 60, 90 So the LCM is 30 because 30 is the lowest number in the list of multiples Ex. 2: Find the LCM of 12 and 18 12: 12, 24, 36 , 48 18: 18, 36 , 54 So the LCM is 36 because 36 is the lowest number in the list of multiples.

5. Least Common Multiple Ex.3 Find the LCM of 5 and 7 Multiples of 5 are 5, 10, 15, 20, 25, 30, 35, 40 Multiples of 7 are 7, 14, 21, 28, 35, 42 Can you find the multiple? The lowest number that is the same in both list. The answer is 35. SOOOO the LCM is 35!!! Easy right!!

6. How to use LCM? When you are looking for a pattern? Example: Ikisha has piano lessons every 3 rd day and swim lessons every 4 th of the month. On what days will she have both piano and swim lessons? First look for a pattern or the LCM of both numbers. Multiples of 3 3, 6, 9, 12, 15, 18, 21, 24, 27, 30 Multiples of 4 4, 8, 12, 16, 20, 24, 28 Circle the lowest common number Answer: on the 12 th day Ikisha will h ave both piano and swim lessons. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

7. How to use LCM? When you are finding a common denominator to add or subtract fractions? This is called a LCM for least common denominator. Notice the denominators are not the same. Use the multiples of 4 and 2 to find the LCM. Multiples of 4: 4, 8 Multiples of 2: 2, 4, 6 4 is the LCM or LCD ¼ + ½ = T o make the denominators the same, you multiply. 1 + 1 x 2 = 2 1 + 2 = 3 4 2 x 2 =4 4 4 4 Do not change 1/4 Now the denominators are alike. Notice the numerator and denominator are multiplied by 2

8. Least Common Multiple Points to remember!! A multiple is the product of two numbers. List the multiples of each number to find the common number. Use LCM to find patterns. Use LCM to add or subtract fractions, the LCM becomes the LCD (the least common denominator).