Numbers are friendly!

Last week we did an investigation around the number 10. We know that it is a friendly number and we want to be able to decompose numbers to make 10 in a quick way. We noticed a pattern when we break/decompose/split numbers 11, 12, 13, 14, 15, 16, 17, 18, and 19.


After reflecting on the pattern and the way the numbers were written, one student thought that maybe 18 with one taken away might be 8. We decided to investigate this idea further today.

We were able to figure out that 18 and one less was 17. Take a look at some of our ideas!