Every idea in this chapter — spotting the pattern, the common difference, the nth term, and the sum — laid out like a ladder blueprint. Climb through the tabs and build your own AP.
A list of numbers is an arithmetic progression only if every term is obtained by adding the same fixed number to the one before it. Read each real‑world pattern, then tap the card to check.
Pick a first term a and a common difference d — positive, negative, or zero — and watch the ladder rungs respond.
Type any list of numbers, comma‑separated, and check whether it forms an AP.
Three everyday questions, one formula. Switch modes to try each.
Gauss's trick: write the sum forwards and backwards, then add — every pair totals the same amount. Slide n to see the pairing, then use the calculator for any AP.