If you need to add up (sum) up race time splits that are some combination of hours, minutes, and seconds, you can simply use the SUM function. The formula in cell H5 is:
=SUM(C5:G5)
However, you must take care to...

To allow only values that don't exceed a set sum, you can use data validation with a custom formula based on the SUM function. In the example shown, the data validation applied to B5:B9 is:
=SUM($C$6:$C$9)<=1000...

To lookup and return the sum of a column, you can use the a formula based on the INDEX, MATCH and SUM functions. In the example shown, the formula in I7 is:
=SUM(INDEX(C5:F11,0,MATCH(I6,C4:F4,0)))
How this formula...

To count unique numeric values in a range with criteria you can use a formula based on the SUM and FREQUENCY functions, together with the IF function to apply criteria.
For example, assume you have a list of employee...

To calculated a weighted average, you can use the SUMPRODUCT function together with the SUM function. In the example shown, the formula in G7 is:
=SUMPRODUCT(C5:C11,D5:D11)/SUM(D5:D11)
How this formula works
The...

If you need to sum or add the bottom values in a range, you can do so with a formula that uses the SMALL function wrapped inside the SUMPRODUCT function. In the generic form of the formula (above), rng represents a...

To sum the top values in a range, you can use a formula based on the LARGE function, wrapped inside the SUMPRODUCT function. In the generic form of the formula (above), rng represents a range of cells that contain...

To sum all values in a column or row, you can use the INDEX function to retrieve the values, and the SUM function to return the sum. This technique is useful in situations where the row or column being summed is...

To sum the last n columns in a table of data (i.e. last 3 columns, last 4 columns, etc.) you can use a formula based on the INDEX function. In the example shown, the formula in K5:
=SUM(INDEX(data,0,COLUMNS(data)-(K4-...

To sum every n rows, you can use a formula based on the OFFSET and SUM functions. In the example show, the formula in F4 is:
=SUM(OFFSET($C$3,(ROW()-4)*5,0,5,1))
How this formula works
In this example, there are 5...

To check to see if a cell contains more than one substring, you can use a formula based on the COUNTIF function.
In the example shown, the formula in C5 is:
=IF(SUM(COUNTIF(B5,{"*abc*","*aaa*...

This examples shows how to calculate a volunteer hour requirement. The requirement is to have 15 volunteer hours, with at least 5 in each category. The formula in F6 is:
=AND(COUNTIF(C6:E6,">=5")=3,SUM(C6...

One way to extract data in Excel is to use INDEX and MATCH with a helper column that marks matching data. This avoids the complexity of a more advanced array formula.
In the example shown, the formula in H6 is:
=IF($...

If you want to sum an entire column without supplying an upper or lower bound, you can use the SUM function with and the specific range syntax for entire column.
In the example shown, the formula in G6 is:
=SUM(D:D...

To sum based on multiple criteria using OR logic, you can use the SUMIFS function with an array constant. In the example shown, the formula in H6 is:
=SUM(SUMIFS(E4:E11,D4:D11,{"complete","pending...