[Maths-Education] Why is reciprocal called 'reciprocal'?

[Dylan Wiliam]

In Welsh, cilydd (pronounced kill-ith, but with the th prounounced as=20
in this, rather than thorn), which means something like companion,=20
or, in a literal translation of another meaning, reflexively=20
effectual.

Dylan

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>Q from an 11-year-old: Why are reciprocals so-called?
>
>(I know that they have the 'mutual' property of reciprocality - but then do
>so many things.)
>
>Can anyone tell me what they are called in French/German/other languages?
>Sometimes that can help with questions such as this.
>
>             Thank you and Best regards
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Dylan Wiliam
Department of Education and Professional Studies
King's College London
=46ranklin-Wilkins Building (Waterloo Bridge Wing)
150 Stamford Street
London SE1 9NN

Tel: +44 (0)20 7 848 3153
=46ax: +44 (0)20 7 848 3182

http://www.dylanwiliam.net
http://www.kcl.ac.uk/depsta/education/KAL/ASSESSMENT.html