Number Tower is a free online number stacking puzzle. Each tower has a little flag with a total on it, and the numbered blocks start piled up any old way. Lift the top block of one tower and set it on another until every flagged tower adds up exactly. The catch is the stacking rule: a block may only go on an empty tower or on a block with the same number or a bigger one, so a big block buried under small ones has to be dug out first. Later levels bring short towers with only a few slots and grey stone blocks that count toward their tower but never move. Every one of the twelve levels has exactly one way to share the blocks into the totals, a computer search sets par so three stars are always possible, and you can never get stuck. Not a merge game — nothing combines; the sums and the stacking are the whole puzzle. No download, no sign-up, works on phones.
How to play Number Tower
- Each level shows a row of towers on a wooden board. Most towers have a red flag on top with a number: the total that tower must add up to. A tower with no flag is a spare and may hold anything.
- The numbered blocks start stacked on the towers in no particular order. The small label under each tower shows its total so far against its flag, for example 9 / 14.
- Tap a tower to lift its top block, then tap the tower to set it on. You can also drag the block from one tower to another. Tap the lifted tower again to put the block back.
- A block may only go on an empty tower or on a block with the same number or a bigger one — never on a smaller number. Each tower also holds only as many blocks as it has slots.
- From level 7 some blocks are grey stone. A stone counts toward its tower’s total but can never be lifted, and only a block with the same number or a smaller one can sit on it.
- When every flagged tower adds up to its flag, the level is done. Finish in par — the fewest moves possible — for three stars, within the two-star line for two; any finish earns one.
- Undo takes back the last move, Start Again deals the level afresh and Hint shows the next move on a shortest route. On a keyboard, number keys pick towers, U undoes, H gives a hint and Esc puts a lifted block back.
Tips
- Do the sums first. Work out which blocks each flag needs before you move anything — on every level there is only one set of blocks that makes all the totals.
- Then plan the order. The biggest block a tower needs has to go on first, at the bottom, because nothing bigger can ever go on top of it.
- Use the spare tower as a parking space, but park small blocks on big ones so the big blocks stay free to move.
- Two blocks with the same number can sit on each other, which is often the quickest way to clear a tower.
- On a short tower, count the slots: if a flag needs three blocks and the tower has three slots, nothing else may visit it on the way.
- A stone fixes the bottom of its tower. Subtract it from the flag to see what the rest of that tower must add up to, and remember only smaller blocks can stand on it.
FAQ
Is Number Tower free to play?
Yes. It runs in the browser with no download, no sign-up and nothing to buy. All twelve levels are included and unlock one after another as you finish them.
Can a block go on a block with the same number?
Yes. The rule is that a block may never sit on a smaller number, so a 5 can go on a 5, a 7 or a 9, or on an empty tower, but not on a 4. Stacking equal numbers is often the quickest way to clear a tower.
Is there only one answer?
Every level has exactly one way to share the blocks into the flag totals — which blocks end up on which tower — so the adding up always has a single answer. There are usually several orders of moves that get there; par is the shortest.
Can I get stuck?
No. On every level, every position you can reach can still be finished, so Hint always has a next move for you. Undo and Start Again are there if you would rather go back.
How are par and the stars worked out?
A computer search tries every position a level can reach and finds the fewest moves to make every flag, so three stars are always possible. The two-star line is the median of 41 runs by a good player who knows the way but makes a wrong move one time in four. Any finish earns one star.
Is Number Tower like the Tower of Hanoi?
It borrows the Hanoi rule that a bigger piece may never sit on a smaller one, but the goal is different: instead of moving one tower in order, you share numbered blocks out so each tower adds up to its flag. The blocks also start in a jumble, and equal numbers may stack.
Is it good for practising mental addition?
Yes. The flags run from 7 to 26 and the blocks are numbered 1 to 9, so every level asks for quick adding and taking away in your head — which blocks make 14? — along with some planning ahead.
Does Number Tower work on a phone?
Yes. Tap a tower and then where its top block should go, or drag the block across with a finger. On a phone held upright the towers sit above the goal and the buttons; on a wider screen the goal sits beside them.