Also bridging the tens would be simple e.g. 23-7 ..... if you knew that 7 -3 =4, you'd presumably be much faster at going 23-3 = 20 and I need to take off another 4
Yes, I can see that learning those facts by rote would make the bridging through 10 much quicker. Think DS knows some of those, but perhaps not all. And hasn't been encouraged to use those facts to bridge through. Think I will do those tests with DS once school starts; think they should receive minimal opposition as they're so nice and short.
I bought Yhatzee yesterday for the evenings/ rainy days of our screen-free holiday next week