It is important for students to understand the basic relationship among digits in the numbers they are adding. When students add multi-digit numbers, they add digits at the same places to get the sum. Add two 5-digit numbers without regrouping worksheet provides plenty of practice with this concept. This worksheet is about practicing with the horizontal format in which numbers are written side by side. To develop flexibility with numbers and operations, students need to have enough practice in this format and not just rely on the vertical/column method.