Problems should use the Courier font. Why? Every Courier font character uses the same amount of space. A comma is the same width as the number 5. This means that all of the numbers line up perfectly for carrying during addition and bringing the zero down in division.
In conclusion, nobody wants to pay for math worksheets anymore. Thatís OK because there are lots of places on the Internet to get freebies. Find arithmetic worksheets that address your needs and provide students with competitive problems sets, FOR FREE!