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Expert's notebook

Only one number in the list is the original. The fakes come from the other players, who saw it, or from the House, which imitates typical mistakes. A few quick checks rule out many of them.

How it works

  • Two roles. The forger sees the question and its original, and has 30 seconds to set a believable fake: a whole number between half and double the original, other than the original itself. After 3 refusals, when time is up, or for an absent player, the House sets a fake in their place: it earns the forger nothing and, in the daily, it never joins the pool of fakes served to the next experts. The expert discovers the question and has 20 seconds to find the original among five notes: the original, the players' fakes and the House's. In Glance, the clock starts with the image, not with the list.
  • The House. It imitates the typical mistakes of each family, listed below, and fills in when needed with values close to the original (2 to 25 above or below). In Arithmetic, Calendar and Glance, once 200 player fakes have been seen for a family and a level, half of its places go to fakes learned from the players: the gaps that fooled the most, applied to the new original.
  • Daily. One question for everyone, every day: you hunt first, then the reveal shows where each note came from, then you set your fake for the next experts: its 30 seconds start at the reveal, on the same page. It is rated the next day at 00:10. A list shows at most 3 player fakes, the least served first, and never a fake from your household (same connection or linked accounts).
  • Season. Each month, your hunt points in the daily and the ratings of your fakes make your season points. Ranked from 8 days played; the prizes (150, 100, 60, then 25 credits down to 10th place) are paid on the 1st of the next month, by place among the ranked players. No place is shared: on equal points, more days played comes first, then more hunt points, then, as a last resort, the older account. A prize needs points: a ranked player on 0 points gets nothing, and the place does not pass to the next one. A guest player is ranked but wins no prize: their place goes to the next member.
  • Room. 2 to 8 players, 5 rounds. Each round has two questions and two groups: everyone sets a fake on their group's question, then hunts the other group's. Live, a reveal follows each round; in turns (12 h for the fakes, then 12 h to hunt), the round details are in the results. The 5th round, the final, counts double. Live, if you arrive late in a phase, you only get the time left. Missing two phases in a row makes you absent: nobody waits for you any more and the House sets your fakes. Leaving the room puts you last, whatever your points (and the stake is lost); with fewer than 2 active players, the room pauses for 120 s, then stops.
  • Duel. One on one, from the Duels page: in turns, each player sets 5 fakes, then hunts the other's 5; live, a room of two where leaving means forfeit.
  • Training. Hunt: 10 questions of one family against the House; Workshop: 5 fakes judged by the bench of checks. The “long time” setting gives one and a half times the time.
  • Screen readers. Arithmetic, sequence and calendar questions are read in full. Figures are described (“3 by 4 grid”) without the detail of their lines, and Glance shows a cloud of dots for 2 seconds: these two families are played by eye. They can be left out in training and when creating a room, not in the daily (figures on Wednesdays and every other Sunday) nor in duels (every family of the level, Glance included).
  • Flagged games. A game leaves the leaderboards, prizes and ratings when a pick comes less than 0.7 s after the list (0.3 s in Glance), when the Glance image is asked for again or stays on screen longer than 4 s, or when half of its picks come in under 0.4 s (at least 5 answers).

Arithmetic

  • Last digit: the last digit of the product of the last digits (47 × 38: 7 × 8 = 56, so the original ends in 6).
  • Casting out nines: the digit sum of the result, modulo 9, matches the computation's. It misses a gap of 9, 90 or 99: 1,696 passes casting out nines and the last digit of 47 × 38 = 1,786.
  • Magnitude: 47 × 38 is close to 50 × 40 = 2,000, a bit less.
  • Parity: even times anything is even.
  • House mistakes, for example: a forgotten carry (47 × 8 written without the carry of 7 × 8 gives 326, then 1,736), two adjacent digits swapped (1,768), a digit off by 1 (1,776). All of them: a forgotten carry, a digit off by 1, two adjacent digits swapped, off by 9, 90 or 99 and the right magnitude and the right last digit. At level 3, at least one of its fakes passes both the last digit and casting out nines.

Sequence

  • Write down the successive gaps, then the gaps between the gaps: 3, 7, 15, 31 gives 4, 8, 16, each one double the last.
  • Look for a rule that explains every term: here each term is double the previous one plus 1, so 63.
  • House mistakes, for example: the last gap repeated (47), the last term doubled (62), a similar rule (65). All of them: the last gap repeated, the last term multiplied, a similar rule, off by 1 and a digit off by 1.

Figures

  • Count by size: a 3 by 4 grid has 12 squares of side 1, 6 of side 2 and 2 of side 3, so 20.
  • Rectangles of a 2 by 3 grid: 3 ways to pick two horizontal lines, 6 to pick two vertical lines, so 18.
  • Triangle in 4 rows: 20 upward triangles and 7 downward ones, so 27.
  • House mistakes: only the smallest shapes, a size forgotten, only the upward triangles, the big shape forgotten, a size counted twice and off by 1.

Calendar

  • Months of 31 days: January, March, May, July, August, October, December; February has 28 days, 29 in leap years (2028, 2032).
  • From March 14 to June 2, 2027: 17 days in March, 30 in April, 31 in May, 2 in June, so 80.
  • A 30-day month shifts the day of the week by 2, a 31-day month by 3.
  • House mistakes, for example: the end dates counted (81), a month counted as 30 days instead of 31 (79). All of them: the end dates counted, or not, a month counted as 30 days instead of 31, or the reverse, off by a week, a month forgotten and off by 1.

Glance

  • The cloud stays about 2 seconds. Big numbers are often underestimated: group the dots by 5.
  • From level 2, never in the daily.
  • House mistakes: an underestimate, an overestimate and off by a few dots.

Points

  • Original found: 1,000 points up to 3 seconds, then less and less down to 500 at 20 seconds.
  • In rooms and duels, each expert fooled by your fake earns you 400 points, shared if other forgers set the same one.
  • In the daily, your fake gets a rating out of 1,000 the next day: 1,000 × 2 × experts fooled ÷ (experts served + 3), at most 1,000, once 3 experts have been served (fewer, it is not rated); each author of the same fake gets the full rating.
  • House fake picked: 300 points off in rooms and duels (600 in the final); picking nothing scores 0. The final counts double, penalty included.

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