Cheating at gangetabel.dk for fun and glory

My son is doing multiplication in school – they're training for speed now, which is actually a great way to just get the basic multiplication down pat without resorting to counting positions in the times tables in your head. You need to know the 1-9x1-9 by rote.

The tool they're using is a web application called gangetabel.dk that simply goes through all the 81 permutations of 1-9x1-9 in random order and times each “run”. The goal is to get everyone in the class under 5 minutes, but a decent time is 3 minutes and change – and there's ice cream for everyone in the class each time a student gets under 2 minutes for the first time.

I got a 1:54 on my first try, which I suppose is to be expected from such a esteemed member of the programmer's guild as myself, math wiz, computer science degree you know, nudge nudge ... but one of my son's friends is just ABNORMALLY fast – I mean 1:36! Honestly! Obviously, this cannot stand! Which means I am now locked in a duel of honour with an 11-year old child I barely know. Rest assured, this is perfectly normal behaviour for me. Obviously I can't beat him at his own game, he plays Fortnite and has reflexes that are not of this world, no no, that would be madness. So I did what any ex-D&D wizard woth his salt would do – cheated. Brain over brawn and deviousness over brain – as it should be.

Adept at hacking all things of the interwebs, I quickly came up with a hack. It's all very basic – and only possible because the important variables and functions in the training game are available in the global Javascript scope, which also made this hack a candidate for yet another of my Javascript bookmarklets. I haven't been a complete ass about it though, so I've made the title of the page blink the word “SNYD” after solving, which is Danish for “CHEATING” (lawful good and all that).

Most importantly, my son was very impressed with my magical hacker abilities, which I consider the definitive victory.

To “install” the dirty rotten cheating bookmarklet, just drag the button below to your bookmarks toolbar (dont click it, it won't do anything, you just drag the whole thing to your bookmarks toolbar).

Solve gangetabel.dk (9x9)

Once the button is in your bookmarks bar, load up gangetabel.dk, pick the 9 x 9 training board and click the button – it should solve the board almost instantly.


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