Skip Counting — Answer Key
Part A: Sort the Words
Sort each word or number into the correct category box.
1. Sort each number into the correct skip-counting group.
Counting by 3s
91218 Counting by 10s
5080100 9, 12, and 18 all land on a count-by-3s jump (3, 6, 9, 12, 15, 18), while 50, 80, and 100 all end in 0 and appear when you count by 10s.
Part B: Fill in the Blank
Write the missing word or number on each line.
1. 3, 6, 9, 12, 15.
The sequence jumps by 3 each time, so the number after 9 is 9 + 3 = 12, which then lands on 15.
2. 30, 40, 50, 60, 70.
Each number is 10 bigger than the last, so after 50 you add another 10 to get 60, which is exactly 10 less than 70.
3. 6, 9, 12, 15, 18.
This is a count-by-3s pattern. After 9 you jump up 3 to land on 12, and 12 + 3 = 15 matches the next number.
4. 60, 70, 80, 90, 100.
Each number goes up by 10, and 90 + 10 = 100, which is the next multiple of 10 after 90.
5. 15, 18, 21, 24, 27.
The jumps are all 3 (15 to 18, 18 to 21), so after 21 you add 3 more to get 24, and 24 + 3 = 27.
Part C: True or False?
Read each statement. Circle True or False.
1. 3, 6, 9, 12 is counting by 3s.
True False
The difference between each pair (3 to 6, 6 to 9, 9 to 12) is exactly 3, so this is a perfect count-by-3s list.
2. 20, 30, 50, 60 is counting by 10s.
True False
The jump from 30 to 50 is 20, not 10. A true count-by-10s sequence would include 40 between them: 20, 30, 40, 50, 60.
3. 10, 20, 30, 40 is counting by 10s.
True False
Each number is exactly 10 bigger than the one before (10 + 10 = 20, 20 + 10 = 30, 30 + 10 = 40), so this is counting by 10s.
4. 3, 6, 10, 12 is counting by 3s.
True False
The jump from 6 to 10 is 4, which breaks the pattern. Counting by 3s from 3 would go 3, 6, 9, 12.