Our familiar digits are called Arabic numerals, though they were developed in India before spreading westward.

The longer version

The digits now used almost everywhere trace back to Indian scripts of the first millennium, where they were paired with a decimal place value system and a working zero. Scholars writing in Arabic translated and extended those methods, and European readers met the notation through those translations rather than the originals.

Hence the misleading label: the numerals are called Arabic in English because of the route they travelled, not the place they were invented, which is why specialists prefer Hindu-Arabic. Letterforms drifted as scribes copied them, so a modern three barely resembles its ancestor. Counting rods and abacus boards gave way once written arithmetic could be checked on paper.

Where this entry sits

This section collects odd corners of mathematics, from stubborn prime numbers to counting systems older than modern schools. Expect famous constants, probability puzzles, shapes that break everyday intuition, and numbers far too large to picture. The full list sits on the Numbers and Math page, where every entry is listed in order.