The first single released to promote the 1981 album 'Computer World' was Pocket Calculator (May 1981). It wasn't the first time for Kraftwerk to release a single in different languages around the world, but not to such an extent. Four language versions were released: German, English, French and Japanese. It seems an Italian version was also prepared, but used only as a playback for some Italian TV appearances in 1981.
There are two different shortened versions of the single: one cuts the album version at 4.35 (on all language versions alike), the other, used in the US only, runs to 3.55. 'Pocket Calculator' was also the first Kraftwerk single to use one basic sleeve design around the world, but there are differences worth pointing out.
Most often used was the basic UK version of the Pocket Calculator sleeve (EMI 5175). Pressings from Italy, Portugal and The Netherlands are alike.
The same basic sleeve design can be seen on the German, French and Japanese versions of the single, all with title in the relevant language.

In Canada, 'Mini Calculateur' (FWB 471) was released as well as 'Pocket Calculator'. Contrary to what is claimed on the label of 'Mini Calculateur', the regular french edit version (4.35 minutes) appears on the disc.

These two releases sometimes appear in the wrong sleeve - probably pressing plant mix-ups.

Interesting releases from the UK include a 12" single, featuring 'Numbers' and the album version of 'Dentaku' in addition to the single cut of 'Pocket Calculator'. The cassette single reverses this order - short 'Dentaku' and long 'Pocket Calculator'.
Toshiba-EMI in Japan pressed a special promo single for 'Dentaku', using the long and short version on the B-side of this 12" shared with Duran Duran.

In contrast to the singles using different language, the Spanish and Mexican pressings use the standard 'Pocket Calculator', despite their title 'Calculadora de Bolsillo'. From Mexico, there is also a 12" single, reproducing the UK 12" tracklisting. The Netherlands released a unique coupling, using the 4.55 minute version of 'Dentaku' on side A and the album version of 'Pocket Calculator' on side B.

Two coloured vinyl pressings of 'Pocket Calculator' can be found. The US 7" has a distinctive clear-plastic sleeve with the sleeve graphics printed in black. To promote this release, Warner Brothers also distributed a promo-only 12" single with the regular design on a white background. The US releases also have the mentioned unique 3.55 cut of 'Pocket Calculator'.
Also pressed on yellow vinyl is a 12" promo single from Colombia (no picture sleeve here), again using the UK 12" tracklisting.

Singles without picture sleeves are known from Brazil (promo-only with 'Computer World' on side B), Ireland, New Zealand and South Africa.
An oddity is a of 'Mini Calculateur' The Netherlands (a 7" probably manufactured for sale in France - with a picture sleeve). The Netherlands also had a 12" of Pocket Calculator, using a unique coupling of the album versions of 'Dentaku' and 'Pocket Calculator' without 'Numbers'.