The Euler Index

Level

Level is the camp your child has reached, 1 to 7. A higher level always ranks above, whatever the other two figures say, and a level once reached is theirs for good.

Accuracy

Accuracy is your child's footing: of the last seventy problems at this level, how many out of 100 your child got right at the first try, without a hint. A new camp starts a new count: at a new Level the seventy first answers begin again, and the Level reached stays.

Altitude

Altitude is how high your child climbs, among the others at the same camp: of every 100 climbers at your child's level — worldwide, unless a switch on the Profile says your child's country, your child's age or both — how many have a footing at or below theirs. Altitude 54 means your child's footing is better than or equal to 54 of every 100 of them. Your child counts in the list and a tie counts in your child's favour, so an Accuracy of 100 reads 100 and nobody reads 0. The climbers counted have at least ten answers at the camp and have played in the last ninety days; their number stands beside the figure. A population with fewer than ten climbers says "Not enough climbers at this camp yet — showing worldwide". The header and the boards show the world. Beside the figure stands its band in words: top quarter is 75 and above, upper half is 50 to 74, climbing is below 50. Altitude moves a lot in the first week, then settles. A population shows a figure, never another child.

Steepness, beside the Index

Every problem has a Steepness: the share of children at your child's level who got it wrong first time, out of 100. It is never set by an author or a teacher; it comes from the children who have tried the problem, and it is only shown after the attempt. Steepness tells your child about the problem; it is not part of the Euler Index.

What moves it

The index shows the last seventy problems, nothing older. It can go down after a hard week and come back up after a good one; that is what practice looks like. How quickly the answers came is never part of it; perseverance and volume are counted in Eulos, not in the Ei. A Level n problem is worth n × n Eulos. A Level is finished after seven adventures; from there Base Camp is where you train, and Base Camp earns no Eulos.

Your child's index shows the last seventy problems, nothing older. It can go down after a hard week and come back up after a good one; that is what practice looks like. The level your child has reached is theirs for good.

Public or private

You choose whether your child's Index is public: the Euler Index switch on the Profile. Off means nothing reaches any public board — not greyed out, not anonymised, withheld. On, a board shows the Euler ID, the alias only with your specific consent, the country, the Index with the age in brackets and the Eulos; never a school, never a name.