1. Multiples, Factors and Prime Numbers!

2. Multiples - Any number has a set of multiples. When a number is multiplied by any whole number (integer) the result is called a multiple. For example the first five multiples of 3 are – 3x1 = 3 3x2 = 6 3x3 = 9 3x4 = 12 3x5 = 15

3. Rules of Divisibility - A number is divisible byIf…Examples 2The last digit is an even number12, 134, 36 3The sum of all digits when added together is divisible by 3 18 1 + 8 = 9 4The number formed by the last two digits is divisible by 4 732 32 ÷ 4 = 8 5The last digit is 5 or 025, 125, 50 6The last digit is even and the sum of its digits when added together are divisible by 3. 3, 426 3 + 4 + 2+ 6 = 15 7No divisibility test 8The number formed by the last three digits is divisible by 8 7, 538 538 ÷ 8 = 67 9The sum of all its digits is divisible by 96, 831 6 + 8 + 3 + 1 = 18 10The number ends in 030, 170, 200

4. Question 14.3 - Use some of the methods for spotting multiples to decide whether the following numbers are multiples of 2, 3, 4, 5, 6, 8 or 9: a) 2652 b) 6570 c) 2401

5. - Factors - The concept of factor is simply the reverse of multiple. For example the factors of 12 are – 1 x 12 = 12 2 x 6 = 12 3 x 4 = 12

6. Prime Numbers - Any number that has precisely two factors, and no more than two, is called a prime number. For example the number 13 can only be made by multiplying 1 x 13. Whereas 12 is a composite number, not a prime number as 6 x 2 and 3 x 4 = 12.

7. Counter Activity - To find out if a number is a prime number and not a composite number you can use counters or draw a diagram. If you cannot make an enclosed pattern with even columns on each side then the number is a prime number.

8. For Example - Thirteen is a prime number as it cannot be arranged to make an enclosed pattern, as shown below. However Twelve is a composite number as it can be arranged to make different enclosed patterns, as shown below.

9. Can you? List all the prime numbers between 70 and 100.

10. Hundreds chart

11. Practice For revision and practice of multiples and prime numbers, the year 3 Mathematics- multiplication skill builder, (F.1-F.11) is available for students, as well as the year 4 Mathematics- prime and composite numbers (A.5) on the IXL website for students (Maths for kids). Students can choose from a variety of mathematics exercises, of different levels and kinds.

12. References: Math-exercises-for-kids.com-Webmaster: Laurent Monnot. Retrieved from www.mathsexercisesforkids.com/ www.mathsexercisesforkids.com/ You Tube. Prime number song. Prime Time (Maths song) Retrieved from: www.youtube.com/watch?v=pGu9cKL-i8 www.youtube.com/watch?v=pGu9cKL-i8 You Tube. Prime numbers song. Prime numbers- The Sieve of Eratosthenes. Retrieved from: www.youtube.com/watch?v=9m2cdWorlq8.c om www.youtube.com/watch?v=9m2cdWorlq8.c om