Children practice adding two 5-digit numbers with regrouping with this worksheet. As students add multi-digit numbers, they often find the need to regroup numbers. They regroup 1 ten into 10 ones, 1 hundred into 10 tens, and so on. Help your students practice this concept and develop conceptual and strategic knowledge with add two 5-digit numbers with regrouping worksheet. In this worksheet, students practice solving problems written in the horizontal format. How numbers are laid out in a problem affects the method a student employs to solve it. Therefore to develop actual fluency and mastery of multiple strategies, students must practice different formats.