Skip Counting, Odd and Even Numbers

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What this lesson covers

  • Even numbers end in 0, 2, 4, 6 or 8. Odd numbers end in 1, 3, 5, 7 or 9.
  • Counting in 3s goes odd, even, odd, even.
  • Some numbers are in two counts, like 10 in the 2s and the 5s.
  • Counting in 10s changes the tens digit. Counting in 100s changes the hundreds digit.
Key idea

Odd and even

  • An even number can be put into pairs with none left over.
  • Look at the last digit. 0, 2, 4, 6 or 8 means even.
  • 1, 3, 5, 7 or 9 means odd.
  • So 534 is even and 827 is odd.
Worked example

Counting forwards and backwards

  • Start on a number in that count. Add or take away the same amount each time.
Count inForwardsBackwards
2s12, 14, 16, 1820, 18, 16, 14
3s9, 12, 15, 1830, 27, 24, 21
4s16, 20, 24, 2840, 36, 32, 28
5s25, 30, 35, 4020, 15, 10, 5
8s8, 16, 24, 3248, 40, 32, 24
Key idea

Try it: skip count

Key idea

Counting in 3s: odd, even, odd, even

  • 3, 6, 9, 12, 15, 18.
  • 3 is odd, 6 is even, 9 is odd, 12 is even.
  • Add 3 to an odd number and you get an even number.
  • Add 3 to an even number and you get an odd number.
Key idea

Where counts meet

  • Count in 2s: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20.
  • Count in 5s: 5, 10, 15, 20.
  • 10 and 20 are in both counts.
  • Every number in the 8s count is in the 4s count too: 8, 16, 24, 32.
Key idea

Try it: shade the counts

Worked example

Counting in 10s and 100s from any number

  • Counting in 10s changes the tens digit. Counting in 100s changes the hundreds digit.
  • Watch when you pass a hundred: 293, 303, 313.
StartCountNext three
47add 1057, 67, 77
352add 100452, 552, 652
286take away 10276, 266, 256
715take away 100615, 515, 415
Key idea

Try it: hop in tens and hundreds

Common mistakes

  • 47 is even because 4 is even.
    Only the last digit counts. 47 ends in 7, so it is odd.
  • Counting in 10s from 295, the next number is 296.
    Counting in 10s adds 10 each time: 295, 305, 315.
  • Counting in 3s gives only odd numbers.
    It goes odd, even, odd, even: 3, 6, 9, 12.
  • Counting back in 4s from 40: 40, 36, 34, 30.
    Take away 4 every time: 40, 36, 32, 28.

Your turn

1

Which of these is even: 357, 471, 538 or 925?

2

Count on in 4s: 12, 16, 20, __

3

Count back in 5s: 45, 40, 35, __

4

Which of these is in both the 2s count and the 5s count: 15, 25, 30 or 45?

5

Count back in 100s: 864, 764, __

Show answer

1. 538 2. 24 3. 30 4. 30 5. 664

Summary

What to take away

  • The last digit tells you odd or even.
  • Skip counting adds or takes away the same amount each time.
  • Counts can share numbers, like 10 and 20 in the 2s and 5s.
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More in Number

Numbers to 1,000: Hundreds, Tens and OnesNotesCounting in Groups, Rounding and EstimatingNotesSkip Counting, Odd and Even NumbersNotesAdding and Subtracting up to 1,000NotesMultiplying and Dividing with GroupsNotesUnit Fractions: One Equal PartNotesComparing Fractions and Finding Equal OnesNotesAdding Fractions and Finding Fractions of NumbersNotesDollars, Cents and Giving ChangeNotes

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