one Nth part; one out of N
Attaches to a number N to express a fraction: N分の1 means 1/N. Used after a number, e.g., 五分の一 (one fifth), 十分の一 (one tenth).
See also: 分の
I ate one fifth of this cake.
Only one out of ten applicants passed.
Variant with Arabic numeral 1; common in informal or digital writing.
Compound of 分 (ぶん, 'part') + の (possessive particle) + 一 (いち, 'one'), literally 'one of N parts'.