These worksheets were created for my 1st and 2nd graders to practice their number sense within 100, but could be used for grades K-4. The worksheets can be used for in class practice, morning work, homework, math centers, etc. This product is 6 worksheets practicing finding one less, one more, ten less, and ten more of numbers within 100 and each worksheet contains 9 problems. This activity is also great to use on an interactive board, my students enjoyed coming to the board and filling in