The Total column is allowFormula: each row uses a
relative formula (=B1*C1, =B2*C2, and so on), and the
last row totals the column with =ROUND(SUM(D1:D5),2). Double-click a
Qty or Unit Price cell to edit it and watch the totals
recalculate. Double-click a Total cell to author a formula: type = then a function
name for autocomplete, click another cell to insert its reference (Shift-click for an absolute
$A$1), or drag the fill handle to copy a formula down (relative references shift per
row). Toggle Show formulas to reveal the sources.