Multiplying matrices — row × column, one entry at a time

A nine-scene guided mini-lesson: check the sizes, then build the answer one entry at a time — 2×2 with 2×2, 2×3 with 3×2, 1×3 with 3×1 and 3×1 with 1×3, plus why AB is not BA. Prev / Next drives the story (← → keys work too) — or press ▶ Play all.