GRADE 5 MATHEMATICS
Last Week’s Answers
Exercise 1. 1.O 2. O 3. E 4. O 5. O 6. E 7. E 8. E 14. O 15. E 16. E 17. E 18. O 19. E 20. O. 9. O 10. E 11. E 12. O 13. O Hello boys and girls, Last week we worked with odd and even numbers. We also listed the factors for given numbers, and identified numbers as prime or composite. This week we will work with multiples and find the Least Common Multiple (LCM).
MULTIPLES
6 x 3 = 18 6 and 3 are factors of 18 18 is a multiple of 6 and 3
In the example above we just listed two multiples of the whole number 6. The were found by multiplying that whole number by any counting For example, to find the multiples of 6, multiply 6 by 1, 6 by 2, 6 by 3, 6 by 4 and so on. … Find the multiples of 5 Multiplication Table: 5 x1= 5 6 x 7 = 42 6 and 7 are factors of 42 42 is a multiple of 6 and 7 5 x 5 = 25 5 x 6 = 30 5 x 7 = 35 The multiples of 5 are 5, 10, 15, 20, 25, 30, 35, …
The three dots mean that the number of multiples can be endless. We can go on and on.
Finding the Least Common Multiple (LCM) 1. Look at the multiples you have listed. 2. Identify the common multiples. 3. Choose the common multiple which is the smallest.
Example 1:
Multiples of 9 are 9, 18, 27, 36, 45, 54, 63, 72,… Multiples of 12 are 12, 24, 36, 48, 60, 72, 84,… Common multiples of 9 and 12 are 36 and 72 The of 9 and 12 is 36.
Exercise
Find the LCM of 9 and 12.
1. List the first ten multiples of the following: (a) 5 (b) 6 (c) 9 (d) 12 (e) 15
2. Find the LCM of: (a) 6 and 9 (b) 9 and 15 (c) 12 and 15 (d) 8 and 14
3. One vegetable truck visits Jean’s community every 5 days and another vegetable truck visits every 6 days. If both trucks visited today, when is the next time both trucks will visit on the same day?
4. If the classroom bell was rung every 10 minutes (allowing you to leave the classroom for the day), but the exit gate only opens every 12 minutes, when would be the first time the children could leave the classroom?
5. What is the smallest number that can be divided by 4, 6 and 9 without leaving a remainder?
Goodbye boys and girls. Until next week.