Formatting
Numbers and dates
Formatting changes how a value displays, not its underlying value. Learn to apply number, currency, percentage, date and decimal-place formats. A key trap: a percentage format multiplies the display by 100 (0.25 shows as 25%), while typing 25% stores 0.25. Also know that changing decimals via formatting does not change the stored value used in calculations.
Text and cell appearance
Apply font, size, bold, italic, underline, colour and alignment (left, centre, right; top, middle, bottom). Use Merge and Center carefully - merged cells complicate sorting and references. Wrap text keeps long text visible within a cell. Traps include confusing wrap text with merging, and assuming alignment changes the value.
Borders, shading and styles
Use borders and fill colour to distinguish headings and totals. Cell styles apply a consistent combination of formats. Copy formatting with Format Painter and clear it with Clear Formats. Remember that conditional formatting applies formats automatically based on rules, without changing data.
Rows, columns and layout
Adjust row height and column width, and use AutoFit to fit content. Traps: widening a column to show ##### fixes the display but is not a calculation fix; and row height may not AutoFit wrapped text unless set.
Rule of thumb
Ask whether the task changes the value or the appearance. Currency, percentage, decimals, bold and borders change appearance only; retyping changes the value.
Worked example
A cell holds 0.5. Applying percentage format shows 50%. Applying two-decimal number format shows 0.50. The stored value stays 0.5, so =A1*100 still gives 50.