Module 3 · Lesson 11

ROUND and percentages

Calculate proportions and control precision deliberately.

A percentage is a proportion

Divide the part by the whole, then apply percentage formatting. Do not multiply by 100 if the cell will also use percentage formatting.

=B2/C2

Round for a reason

ROUND changes the stored result, while number formatting changes only what is displayed. Use ROUND when downstream calculations need fixed precision.

=ROUND(B2/C2,2)
  • Check for division by zero.
  • Choose a meaningful number of decimals.
  • Keep full precision when it matters.

Key takeaway: Store percentages as decimal values and use ROUND only when the business result needs controlled precision.