Task your little mathematicians to crack the code of adding and subtracting two 3-digit numbers with regrouping with this fun worksheet. Students use the relationship between addition and subtraction to find the missing number in this worksheet. They also need to regroup numbers to get to the answer in add and subtract two 3-digit numbers with regrouping worksheet. This worksheet is about practicing the column method in which numbers are written one on top of another. In this method, students use their place value understanding to solve the problems.