Mental multiplication

Prime Factor 64

Practice the same 64 multiplication facts in two games. Revisit missed facts in Prime Factor 64, or learn the patterns in the guide below.

Expression Result 13 × 17 221

Read and practice

Practice guide

Learn the 64 facts

Four mental-math moves, worked examples, and a recall drill in both directions.

Project history

How we built Prime Factor 64

The design and technical history, from the first matching boards to practice across sessions.

Project history

How we built Fog Sweep 64

From the two-board prototype to progressive reveals, round reviews, and the final fanfare.