Curated OER
Addition - Three 2-Digit Numbers
In this addition practice instructional activity, students practice their computation skills as they solve 25 problems that require them to add 2-digit numbers. Each problem has 3 addends.
Other
Project Happy Child: Free Subtraction Worksheets
2000 basic subtraction worksheets are available at this web site. They can be printed and used for a variety of practice purposes. Some helpful hints are included to avoid mindless practice that could quickly become counter productive.
Math Aids
Math Aids: Subtraction Worksheets
Great resource for learning and practicing subtraction. Math worksheets are printable, may be customized, and include answer keys.