in French, 92 is quatre-vingt douze or “four twenties and twelve”. And in Danish, the word for 92 is tooghalvfems, where halvfems, meaning 90,is an abbreviation of the Old Norse word halvfemsindstyve, or “four and a half times twenty”

And in English, words like “twelve” or “eleven” don’t give many clues as to the structure of the number itself (these names actually come from the Old Saxon words ellevan and twelif, meaning “one left” and “two left”, after 10 has been subtracted).

Numbers in the modern Welsh system are very transparent. Now, 92 is naw deg dau, or “nine ten two”, much like the system used in East Asian languages. In the older, traditional system, (which is still used for dates and ages), 92 is written dau ar ddeg a phedwar ugain, or “two on ten and four twenty”.

In other languages, the tens and units of numbers are inverted. For example, in Dutch, 94 is written vierennegentig (or “four and ninety”), and other research suggests this may make it harder to do certain mathematical processes.

For example, Dutch kindergarten children performed worse than English children on a task that required them to roughly add together two-digit numbers. This was despite the fact they were slightly older and had better working memory, because Dutch kindergarten starts later than in the UK. But on nearly every other metric, including counting ability, roughly adding and comparing quantities of dots, and simple addition of single-digit numbers, the two groups performed at the same level.

when the children see a number like 38 on the task, they vocalise it internally, and then picture its position on a mental number line. In Dutch, the extra mental step of having to un-invert the number “eight and thirty” before they can assess its value creates extra cognitive strain, and this affects their performance.