This is great for practicing subtraction with manipulatives and numbers. Teachers should model first and encourage borrowing from the tens before removing ones. This matches the program conceptually to the standard algorithm (crossing out the ten and showing the movement of ten ones to the ones place).
Once you understand what the facts mean, practice all facts. You can print a worksheet for extra practice.
These games are addictive! Solve the problems before the piles get too high.
This site has links to dozens of other sites that kids can use to practice basic facts once they have a solid conceptual understanding of multiplication.
Select the operation, & drag numbers to work the problem. It's like working them with pencil and paper, but it's self checking. The only disadvantage is that when you miss one, the problem goes away, so there's no reflection time.
Great near Halloween! Set values for +, -, X, or /. Use to skip count, count forward or backward by one, for divisibility, writing equations, function tables, etc.