How it works
Skip counting by 9 follows one rule from 9 to 90: the tens digit goes up by 1 and the ones digit goes down by 1. This chart lights the 20 stops to 180. Each jump has a note in the list further down.
Read the full guide
Tens up, ones down
Adding 9 is adding 10 and taking 1 away, so from 9 to 90 the two digits of every stop add up to 9. The second five stops are the first five with their digits swapped: 45 and 54, 36 and 63, 27 and 72, 18 and 81. The rule slips once, at 99, whose digits add up to 18.
Two diagonals on the chart
On the 9 skip counting chart, each stop from 9 to 81 sits one row down and one square left of the last. At 81 the diagonal hits the left edge, so 90 stays in that row and a second diagonal runs down to 171.
- Adding 9 in your head: go one row down the chart for 10, then one square back. 63, 73, 72.
- Hold up ten fingers and fold down the fourth: three stand on its left, six on its right, 36.
- Is 468 a stop? Add its digits: 4 + 6 + 8 = 18, a stop itself, so yes.
Questions and answers
Why do the digits of 99 not add up to 9?
Tens up and ones down needs a ones digit to take 1 from, and 90 has none, so the 9 lands whole in the ones place: 99, whose digits make 18. From 108 to 180 the digits add up to 9 again.
Does skip counting by 9 help with the 9 times table?
Yes. The stops are the answers. For 7 × 9 the tens digit is one less than 7, so 6, and the ones digit brings the total up to 9, so 3. The 9 times table chart lists every fact.
Can I print the 9s with gaps to fill?
Yes. Under the strip, Print 6 counting strips gives one sheet of six strips of the 9s and a key on a second. Print the chart gives the chart only. Whole sheets of rows are on skip counting worksheets: choose Count by 9s to 108.