Prior to decimalisation (specifically the decimalisation of British and Irish currency).

(mathematics) A decimal representation of a real number that, at some point, becomes periodic (and repeats some sequence of digits infinitely)

(idiomatic) ten, a group of ten

(dated) A binary (base-2) numeral. / (informal) Used other than figuratively or idiomatically: A decimal (numeral written as a concatenation of successive negative powers of the base) in base 2..

Alternative spelling of predecimalization

(computing) A storage mode that places two decimal digits into one byte, each digit occupying four bits. The sign occupies four bits in the least significant byte.

(typography) A period/full stop ⟨.⟩ or middot ⟨·⟩ used to set off the decimal or fractional part of a number. / (typography, inexact) Any decimal mark, inclusive of commas, separatrices, etc.

(mathematics) A number expressed in the decimal system (base ten), (particularly) fractional numbers so represented.

(arithmetic) Arithmetic using decimal numbers.

plural of decimal point