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Sideways — a total decided in advance

Numbers on an easel. A freely built sum. Your date at the bottom.

A few numbers have been standing on an easel all through the meal, with a total pencilled underneath and a question mark beside it, so that somebody has been quietly checking the addition. At the end you rub the total out, and ask people to call a digit from each line to make three new numbers. Every choice is free. The three numbers are added up, and the answer is today's date — the one you wrote in a sealed envelope before anybody sat down.

This page does the working for any number you want to force, and walks through each stage of it, so you can see both what to write and why the ending cannot move.

1

The number you are forcing

:

Three digits to twelve, which is everything these menus can make, up to a full date and a full time with seconds. Times are read as 24-hour however your browser chooses to show them, and books are numbered in the order they come, Genesis 1 to Revelation 66, so John 3:16 is 43 3 16.

Bites are how many times you subtract. Each bite leaves another number on the stack and so another digit on every easel line, which is the knob to turn if three-digit lines are giving the method away: four numbers make the easel lines four digits long, and the room calls four rounds instead of three. The numbers you subtract are genuinely free — type your own if you would rather write figures you find easy to remember, or press New working until a set looks right on the page.

2

Take two bites out of it

Subtract any number. Subtract another from what is left. Keep the two numbers you subtracted and the number left over — the three marked below. They must add back up to the number you started with, because that is where they came from.

3

Turn the columns sideways

Write the numbers one under another and read each column downwards instead of each row across. Hover or tap a column to see where it lands.

→read down

    4

    On the easel

    This is what stands in the room. The lines, a total, and a question mark — which is the bait. Somebody will check it, find it right, and stop thinking about the numbers altogether. The total has nothing to do with the ending; it is there to be rubbed out.

    5

    The free choice

    Rub out the total. Now ask for one digit from each line, and write them down the page in line order — line 1 gives the first digit, line 2 the second, and so on. Cross each digit out as it goes, so it cannot be called twice. Round two can be a different person, and the last round writes itself from the digits left over. Click any digit below to have it called.

    One line at a time is how it goes in the room: only the line you are asking for is open, top to bottom, round after round. Any order unlocks the whole board, for satisfying yourself that the order really does not matter. Switching between them starts the deal again.

    6

    Why it works

    Performing it