Speed! - Patterns in the Cards - Nine Speed

This is the eighth and last post in the series of posts. - Speed! Patterns in the Cards - I created the fun card game Speed! to teach multiplication. It uses skip counting to teach children to multiply and how to multiply faster. The series of Patterns in the Cards blog posts are meant to show some simple activities that can aid in number sense development using the Speed! cards.

Nine Speed
Lay your cards out like this. What patterns do you see?

Here are the patterns I found with my son.
1. You can count from 0-9 with the ones digit. Start at the last card and go backwards. Let me write it differently so it's easier to read.

9 - 8 - 7
6 - 5 - 4
3 - 2 - 1
0

2. You can count from 0-9 with the tens digit. Start at the first card. Let me write it differently so it's easier to read.

0 - 1 - 2
3 - 4 - 5
6 - 7 - 8
9

Do you think these patterns would continue if we added more cards? Continue laying out Nine Speed cards with the backs up while counting by nines in your head or writing the numbers on small slips of paper.

  99 - 108 - 117
126 - 135 - 144
153 - 162 - 171
180
189 - 198 - 207
216 - 225 - 234
243 - 252 - 261
270

The patterns do continue! The ones digit repeats and the tens digit continues to increase.

Another interesting thing about the nines is that if you add the individual digits for any card together the result is a nine or a number divisible by 9. For example 63 is a card in Nine Speed. 6+3=9. 135 is another number you reach when counting by nines. 1+3+5=9.

Did you find any more patterns? Can you lay your cards out differently and find more patterns?

Do you remember the patterns in Three Speed and Seven Speed? They also contained each number in the ones digit column. Even number Speed cards only contained the digits 2, 4, 6, 8 and 0 in the ones digit and Five Speed only contained 0 and 5.

Next week we will begin finding patterns using two decks of Speed cards at the same time. We will begin with Two Speed and Five Speed.