Quick tips

• Name the shape first. SUM, COUNT, AVERAGE for totals; the IF versions (SUMIF, COUNTIF) as soon as there's a condition.
• Mind the argument order. SUMIF(range to test, condition, range to add). SUMIFS puts the range to add first.
• Exact lookups. VLOOKUP needs FALSE (or 0) as its last argument for an exact match; XLOOKUP is exact by default.
• SQL reads in order. SELECT what, FROM where, WHERE which rows, GROUP BY, then HAVING for conditions on groups.
• Use the hint wisely. Half points beats a lost life: take the hint when you can't picture the function.