Khan Academy
Khan Academy: Add and Subtract Within 100 Word Problems 1
Practice adding and subtracting to solve word problems. These questions are result unknown or change unknown problems. Numbers used are 100 or less. Students receive immediate feedback and have the opportunity to try questions...
Khan Academy
Khan Academy: Find the Missing Number (Add and Subtract Within 100)
Practice solving problems like "___ - 45 = 27" where you have to figure out the missing value in an addition or subtraction equation. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video...