How do you sum multiplied columns in Excel?

To sum multiplied columns in Excel, you'll typically use a combination of multiplication operations and the SUM function. Here's how to do it:

Methods to Sum Multiplied Columns

There are several ways to accomplish this, depending on how your data is organized:

This is the most straightforward approach if you need to see the individual products.

Create a Helper Column: Insert a new column next to the columns you want to multiply (e.g., if you want to multiply Column A and Column B, insert a new column C).
Multiply in the Helper Column: In the first cell of the helper column (e.g., C2), enter the formula =A2*B2. This multiplies the values in A2 and B2.
Fill Down: Drag the fill handle (the small square at the bottom right of the cell) down to apply the formula to the rest of the rows in your data. Alternatively, double-click the fill handle. Column C will now contain the product of each row from Columns A and B.
Sum the Helper Column: In a cell where you want the total sum, use the SUM function to add up all the values in the helper column. For example, =SUM(C2:C100) will sum the values from C2 to C100.

The SUMPRODUCT function provides a more concise method and avoids the need for a helper column.

Enter the Formula: In the cell where you want the total sum, enter the SUMPRODUCT formula. For example, to multiply Column A by Column B and then sum the results, use the formula =SUMPRODUCT(A2:A100, B2:B100). This formula multiplies the corresponding cells in the specified ranges (A2*B2, A3*B3, A4*B4, etc.) and then sums all the products.

While SUMPRODUCT is generally preferred, array formulas can also be used.

Enter the Formula: In the cell where you want the sum, enter the formula =SUM(A2:A100*B2:B100).
Enter as Array Formula: Instead of pressing just "Enter," press Ctrl+Shift+Enter. Excel will automatically add curly braces {} around the formula, indicating it's an array formula (e.g., {=SUM(A2:A100*B2:B100)}). Do not type the curly braces yourself.

Note: Array formulas are less efficient than SUMPRODUCT and can slow down your spreadsheet if used extensively.

Helper Column Method: Column C is calculated as A*B. The sum would be =SUM(C2:C4), resulting in 68.
SUMPRODUCT Method: =SUMPRODUCT(A2:A4, B2:B4) would directly calculate (2*3) + (4*5) + (6*7) = 6 + 20 + 42 = 68.

Helper Column: Use if you need to see the individual products for analysis or auditing.
SUMPRODUCT: Use for a clean and efficient solution without needing extra columns.
Array Formula: Avoid unless you have a specific reason, as SUMPRODUCT is generally better.