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Zero21 is a free online number puzzle card game. Pick number cards to add or subtract from your total - but keep it between 1 and 20. Clear the whole board to win this brain-teasing card solitaire.
Zero21 is a free online number puzzle game with a card-solitaire twist. Pick number cards to add or subtract from the running total - but keep it between 1 and 20. Clear the whole board to win this quick brain-teasing puzzle. Every round plays like a mini mental math workout: spot the right order, grab the special cards at the right moment, and empty the table before the total slips out of range.
The goal is simple: clear every card from the board. Tap a card and its value is added to (or subtracted from) the running total. Your total must always stay between 1 and 20 - drop to 0 or push past 20 and the round is over. Three special cards change the game: MIN sets your total to 1, MAX sets it to 20, and MID brings it back to 10. Plan your order the way you would in a solitaire-style card game: which card to take first, and which numbers to leave for the end.
PC: click a card to pick it up. Click again to confirm your move.
Mobile: tap a card to select it, then tap to confirm. The whole game runs in your browser - no app to install.
Newcomers can jump in with zero rules to learn - just keep the total between 1 and 20. Casual players get a relaxing number puzzle for short breaks. Math fans will enjoy the planning layer: every round is a fresh mental arithmetic challenge that rewards thinking ahead.
Quiet concentration. The board starts full of cards and every pick nudges the total closer to the edge - one wrong card and the run is over. Landing the perfect MIN or MAX at the last moment is a small victory every time. A calm, satisfying number game puzzle that fits between tasks.
Keep the momentum going with more math puzzle games on KickerGames - favorites like 2048 Cupcakes and Piles of Mahjong are a tap away. Pro tip: keep a negative card in reserve near the top of the range - it is your fastest escape when the total climbs.
Yes, Zero21 is completely free to play. Jump in whenever you like and replay any round as many times as you want.
No, Zero21 is not blackjack. It is a number puzzle game: you pick number cards and keep the running total between 1 and 20. The name comes from the total range you need to stay inside, not from card game 21.
Yes. Zero21 works on any device with a modern browser - tap the cards with your finger on mobile, or click with a mouse on desktop.