Here are a few sites you can use to train your child in Math:
1. Math Trainor
This tool was initially made for training MTAP participants. The latest version has exercises for the following:
- 3-digit Addition
- 1-digit Multiplication
2. Techie Math Teacher
This is a free resource. The author of this website has generously posted MTAP and Olympiad questions plus the solutions to each question.
The free version will give you access to the 10 free questions daily. If you subscribe to the monthly or yearly plan, you will have access to practice MTAP and actual MTAP questions from previous years. This is a good resource for those who want to qualify for MTAP.