If you do want to produce your own worksheets and don't have the Microsoft software, you can download free tools like OpenOffice or use an online word processor or spreadsheet such as the free Google Docs which help you do similar tasks. You just need to create a table with as many rows and columns as you need and then type in some numbers before printing it off for your children to practice _ depending on the level of complexity choose single digits or multiple digits. If you're not sure what level to start at, aim low, start with easy numbers and see how your child goes, the self_esteem boost they'll get from acing the first worksheet will give them confidence for more difficult math problems.
The present generation seems to be blessed immensely with intellect and the benefits of mastering math are something worth considering. It is a well_known fact that math is not a subject that one learns by simply reading the problems and its solutions. In order to master the subject, earnest practice on multiple problems is the best way to go. However, not every person is bestowed with required materials like math worksheets to receive adequate amount of practice.