A Free Alternative to the 24 Game

The 24 Game challenges you to wrestle four numbered cards into exactly 24 using + − × ÷ and every card exactly once. Rigid Digit keeps that same exact-answer spirit but widens it into a full daily puzzle: five numbers instead of four, and a different, usually bigger target every time instead of always 24.

It's been played as a card game in Shanghai since at least the 1960s, often called 24 Points there, and in 1988 Robert Sun, who grew up there before moving to the US, turned it into Suntex International's 24 Game, a numbered-card deck rated by difficulty that's now a fixture of American classrooms too.

Rigid Digit actually started as a tribute to Countdown's Numbers Round - you can read the fuller story.

Came to numbers puzzles by way of NYT's Digits instead of Countdown? Rigid Digit fits that too - here's how it compares.

How It's Different

The core idea carried over, but a few things didn't:

• Five numbers, not four. One more number than 24, but still no more than four steps, which is about as much as most people can hold in their head at once.
• A different target every time, not always 24. Every puzzle has its own target, usually much bigger than 24, so there's nothing to memorise or look up.
• Solo, not a race to shout first. Classic 24 Game play is a race: first to call out a correct answer wins the hand. Rigid Digit is untimed and solo, so there's no one else's speed to beat.
• Instant, and reversible. Tap two numbers and the maths happens for you, correctly, so exploring costs nothing but taps, no deck to reshuffle if a path doesn't work out.