This video describes how to use the partial sums strategy with addition. The problem in this video requires regrouping; however, the partial sums strategy eliminates the regrouping procedure. The partial sums strategy is typically performed left to right and focuses on adding only part of each multi-digit number at a time (e.g., only adding digits in the hundreds column to determine the partial sum of hundreds, followed by only adding digits in the tens column to determine the partial sum of tens, and so on). It may be especially important for students to know and understand the partial sums strategies if they have not yet developed an understanding for regrouping. This strategy is also efficient when all or most of the numbers have the same number of digits.