numeral
one
A1
'eins' is the cardinal numeral 'one'. Used as a standalone number ('eins') and contrasts with the indefinite article 'ein' before nouns. Not declined as 'eins' but 'ein' agrees in gender/case with noun. Also used in counting and idioms. No plural; numeric value: 1.
Examples
Eins ist die kleinste natürliche Zahl größer als null.
One is the smallest natural number greater than zero.
Der Schüler bekam die Note eins, obwohl er weniger gelernt hatte, weil er krank gewesen war.
The student received a grade of one, although he had studied less because he had been ill.
Details
Mnemonics
Picture a single object with a big '1' to link to 'eins'
sounds like English 'eins' ~ 'eins' pronounced like 'ines' — remember it's one
Notes
Used as a standalone numeral (versus 'ein' which is an article).