Montessori Addition Worksheets Link
Montessori Subtraction Worksheets Link
UPDATE: These no longer work, but good news... I made a whole series of Montessori Style addition and subtraction pages for my youngest daughter that are free over at my new location, homeschoolden.com. These links will take you there! ~Liesl
My old post which has a quick picture of the worksheet (and a picture of a neat math clock you and your child can make).