The common Germanic numerals from 70 to 90,
*seftenhund, *ahtohund, *newunhund,
became in West Germanic,
*sebuntohund, ahtohund, niuntohund (under the influence of ahtohund), and by dropping the ending, sibenzo, ahtozo and niunzo.
In the ninth century this became sibunzug, ahtozug, niunzug, leading to modern German
siebzig, achtzig and neunzig