Provide opportunities for your child to practice multi-digit addition. Ask him/her to look in a magazine or newspaper for numbers greater than one hundred and choose two of the numbers and to add them together (or subtract), then to explain each step.
Use a deck of cards (without the 10’s or face cards) to practice addition. Have your child turn over two or three cards to create a two- or three-digit number, and then have him turn over two or three more cards to create another number. Ask him to add the two numbers. Play another round, but this time, subtract.