In mathematics, arithmetic or plain old numbers a tenth is one part of a unit or one divided equally into ten parts. A tenth is the reciprocal of ten. A tenth is written as a decimal fraction thus 0.1 and as a vulgar fraction as 1/10.

Tenth is also the ordinal number, being occurrence number ten, following ninth and preceding eleventh. The ordinal number tenth is written 10th.

In music or music theory a tenth is the note ten scale degrees from the root of chord and also the interval between the root and the tenth.

In music a tenth is a compound third.