ionumbers – Restyle numbers in maths mode

‘ion­um­bers’ stands for ‘in­put/out­put num­bers’.
The pack­age restyles num­bers in maths mode. If a num­ber in the in­put file is writ­ten, e.g., as $3,231.44$ as com­monly used in English texts, the pack­age is able to restyle it to be out­put as $3\,231{,}44$ as com­monly used in Ger­man texts (and vice versa). This may be use­ful, for ex­am­ple, if you have a large ta­ble and want to in­clude it in texts with dif­fer­ent out­put con­ven­tions with­out the need to change the ta­ble.
The pack­age can also au­to­mat­i­cally group dig­its left of the dec­i­mal sep­a­ra­tor (thou­sands) and right of the dec­i­mal sep­a­ra­tor (thou­sandths) in triplets with­out the need of specif­ing com­mas (English) or points (Ger­man) as sep­a­ra­tors. E.g., the in­put $1234.567890$ can be out­put as $1\,234.\,567\,890$.
Fi­nally, an e starts the ex­po­nent of the num­ber. For ex­am­ple, $21e6$ may be out­put as $26\times10\,^{6}$.