Arithmetic Grade Three

Lesson One hundred and three: Multiples

You've probably done count-bys before. Look at some of these examples to get an idea of what we're talking about: 

  Counting by 2's: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20

  Counting by 4's: 4, 8, 12, 16, 20, 24, 28, 32, 36, 40

  Counting by 7's: 7, 14, 21, 28, 35, 42, 49, 56, 63, 70
Understanding count-bys should help you to understand multiples. If we can count by 4 and get to 20, then 20 is a multiple of 4. We know that 22 is not a multiple of 4 since when we count by 4 we skip over 22. 

   25 is a multiple of 5 because 25 / 5 = 5 (without any remainder).

   27 is not a multiple of 5 since when we divide 27 by 5 we get a remainder.

   30 is a multiple of 6 because 30 / 6 = 5 (without any remainder).

   41 is not a multiple of 6 since when we divide 41 by 6 we get a remainder.
If a number is a count by of another number, it is divisible by the count by number.

For instance: 


  Counting by 8's: 8, 16, 24, 32, 40, 48, 56, 64, 72, 80, 88.

  We can look at the list and see that 48 is a multiple of 8.

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