I have to confess that math is a weak area over here. It's not ever been my fave and it's really not Baker's either. Reading and history are more up his alley. Needless to say, I'm always on the lookout for ways to make math F-U-N. If it's free, I practically do a dance of joy. I have found several. I hope they help you, too!
I don't remember how I found this site but regardless, we love it. Baker was having a great time playing games. We even played some together. There are lots of great things about on-line activities but this time of year, the biggest bonus for me is that he can be working while I wrap, work on Christmas cards and so forth. There is more than just math games here, by the way. One caveat, the Google thumbnail ads blend in a little too well with the game thumbnails so you will want to be close by to make sure that your child goes where you intend.
If your family is like mine, the littles want to do whatever the biggers do. This is a cute way for the littles to feel "big" and learn. This would be a great way to keep all them occupied - the biggers can teach the littles. Again, there is more than math here. Since it's a Fisher-Price site, there are specific toy ads on the side but they are on the sides of the page, not mixed in with the games.
This site has games for K and up. Baker enjoys this site as well. Again, ads but they are on the side so it's pretty clear where to click to get a specific game. There are worksheets available as well. I try to keep the focus on the lesson on the math as opposed to math plus writing the digit(s) so I use worksheets sparingly.
This site has TONS of stuff that is free and/or very low-priced. For example, I paid 75 cents for some winter-themed skip counting cards, sent the document to Staples for printing (since my printer has tiny ink tanks), cut and laminated them at Mardel. Suddenly something as tedious as practicing skip counting became fun to Baker. It was a small investment of time and $$ but it's a reusable, versatile resource. I can use these as a "center" and have him put them in order on the floor or in the pocket chart. They could be slipped onto a ring or into a photo album instead of laminated and used as a flip book.
You probably have games on hand. Games are a great way to reinforce math skills without the kiddos even knowing it. Chutes and Ladders is a classic. I've even done something as simple as taking the larger, foam dice with digits (instead of dots), we each roll one and the person with the highest digit wins that roll. We keep score using tick marks (another skill to reinforce) and the first one to win 10 rolls is the winner. Baker LOVED this and it was so easy to do.
Many publishers have sticker books that are focused on math skills. Baker loves these. Usborne has a couple that we have been using periodically just to add a little fun.
May all of you have a blessed Christmas!