Beginner

Calculate a percentage change

Find out how much a value grew or shrank, as a percentage.

What you'll build: the percentage change between an old and a new number.

What you need: Nothing but this page.

Why this matters: percentage change is everywhere — prices, scores, growth.

Step 1 — The raw difference

Sales went from 200 to 250.

=250-200 // => 50

Step 2 — As a fraction of the original

=(250-200)/200 // => 0.25

What just happened: parentheses force the subtraction to happen first, then we divide by the original 200. 0.25 means 25%.

Try changing…

Your own old and new numbers.

You learned

Parentheses control what happens first.
(new - old) / old is the percentage change as a decimal.

Next: Simple invoice

Average a set of grades

Use AVERAGE to turn a list of test scores into a single grade.

Build a simple invoice line

Calculate a line total with quantity, price, and sales tax.

On this page

Step 1 — The raw difference Step 2 — As a fraction of the original Try changing…You learned