Every formula in Excel or Google Sheets starts with an equals sign, and functions like SUM(), AVERAGE(), COUNT(), MIN(), and MAX() handle the most common aggregate calculations across a range of cells, such as =SUM(B2:B50). The IF function, written as =IF(condition, value_if_true, value_if_false), adds conditional logic -- for example, =IF(B2>50000, "High", "Low") labels a value based on a threshold. COUNTIF and SUMIF extend this further by counting or totaling only the cells that meet a specific condition, such as =SUMIF(C2:C50, "Lagos", B2:B50) to total sales only from rows where the city is Lagos. Mastering this handful of functions covers the majority of everyday spreadsheet tasks before moving on to more advanced lookups.