Here’s a quick activity you can throw together in two minutes with a pack of number stickers, like the ones here.
You can write numbers on a sheet of paper and have your child put the sticker over the matching number.
You can make dots and have your child count the dots and put the sticker on the correct set of dots.
You can make computation problems and use the stickers as the sum. Or you can leave a blank equation and have your child put a sticker in the blank.
This activity was enjoyed by both my almost four year old and seven year old.