Simple Trick in SCAN Function - Excel:

The input data includes sales information.

Our objective is to compute the Running Total.

Typically, we initialize initial_value (accumulator) as 0 and then iterate through array (current value), accumulating the sum at each step. 

If the initial_value argument is omitted, the function will use the first value in array as the initial_value and begin iterating over the remaining values.

=SCAN(0,B3:B13,SUM)

can also be expressed as,

=SCAN(,B3:B13,SUM)

Both formulas yield the same outcome, though the latter achieves it with one fewer iteration.

This trick can also be applied within the REDUCE function.