I love Rightstart Card games for drilling math facts. There is a totally fun game called Corners. You have to make 5, 10, 15, or 20 by putting two numbers of the same color together. You then keep score by ... I forget the term, but it's all mental math and you right down only the answer (running total?). You can do it w/ addition or subtraction.
My 5yr old loves it. He uses strategies such that 75+15, he do 75+10=85+5=90 or he might do 75+5=80+10=90. You can also start at say 1000 and subtract scores mentally.
there are many other games in the book for multi, div, fractions etc.
I found while my son was quick at these games, it was much slower on worksheets. Most of the hang up is handwriting speed and translating visual problem vs oral problem of the games, onto the paper.
