This packet contains 6 worksheets that practice adding two-digit numbers; knowledge of regrouping is required. Each worksheet contains 9 upside down triangles made of bubbles in which students add the numbers in adjacent bubbles, working their way to the final answer at the bottom of the triangle. My students enjoy the challenge of working through the triangle to get the correct answer. Each worksheet contains 90 addition problems -- but because of the format, my students view it as a challenging game rather than busy work. An answer bank is provided so students can self-check their answers. Answer keys included.