The hook
The 24 game rewards speed; Countdown to Zero rewards taste. Five numbers and a target appear, and any subset combined with +, −, ×, ÷ that lands exactly on the target counts as a solve — but the app tracks how many operations you needed to get there, and fewer is better. Grinding out a five-number, four-step monster feels like work. Spotting the two-number, one-step solution hiding in plain sight feels like a magic trick, and the app tells you exactly how much better your trick was than the "expected" par path.
A sample round
1 · Five numbers, one target
2 · Dad's four-number route
3 · Riya beats par by two steps
How a round plays
- Five numbers and a target appear; combine any subset with +, −, ×, ÷ to hit the target exactly.
- You don't have to use every number — fewer numbers and fewer operations score higher.
- Today's par is the "expected" solution's operation count; beat it for bonus points.
- Division must come out even — no rounding, no decimals.
- Share your winning expression's shape — operation count and a trophy — without spoiling the numbers used.
Why it's sticky
The par system converts a pure math puzzle into a taste contest: everyone who solves it gets the same 100%-correct feeling, but the person who found the shortest path gets to feel clever, and that gap is what people chase. It also naturally scales across ages — a kid can grind out a valid five-number, four-step answer with patience, while an adult competing on elegance has to actually stop and look for the shortcut. Daily par-beating becomes its own small streak within the streak.
Modes
- Daily — one shared number set and target, streaks and share grid in localStorage.
- Practice — unlimited random number sets with adjustable target difficulty.
- Speed countdown (party) — pass the phone with a running timer; first valid expression locked in wins the point.
Build notes
Size: S. The shared shell provides the daily-seed picker, streak/stats store, share-grid generator, and how-to-play screen. Game-specific work is an expression validator that evaluates the user's built expression tree directly (never string-eval), rejecting non-integer division and divide-by-zero, plus an operation-count par solver — a search over subsets and orderings of the five numbers — that runs at puzzle-generation time, the same pattern Rungs uses for its BFS par solver, so the shipped daily puzzle already carries its par. Core logic is a plain JS module, decoupled from the tile-tapping UI, so a future link-shared duel mode can reuse the same validator.