› worksheets › grade_1Free 1st Grade Math Worksheets - Homeschool Math Two-Digit Addition. Students should be provided a 100-bead abacus or base ten blocks for these two-digit addition problems. The problems can even involve a regrouping, or making a new ten, but students are not solving the problems by writing the numbers under each other (adding in columns). The idea is just to use the manipulative to add.