Students must understand the fundamental relationships between the digits in the numbers they are subtracting. They subtract the digits at the same places to get the difference of multi-digit numbers. There is lots of practice with this concept in subtract two 4-digit numbers without regrouping worksheet. As the worksheet uses a horizontal format, it allows for more creativity when it comes to how the student solves the problem. In contrast, in the vertical format, students usually employ the standard method to solve.