Multiplication sign (×)

How to read it

OpenStax’s Prealgebra reads 3 × 8 as “three times eight” and lists the other ways to write multiplication: a dot (3 · 8) and brackets. The sign is U+00D7, MULTIPLICATION SIGN, a separate character from the letter x. It also stands between dimensions, as in NIST’s 51 mm × 51 mm × 25 mm.

Also searched as: ×, multiplication symbol, times symbol.

× or the letter x

Unicode cross-refers × and the small letter x (U+0078) both ways. The resemblance put Leibniz off: in a letter of 1698 he wrote that × “is easily confounded with x”, and marked multiplication with a dot instead. Other crosses that are not the multiplication sign include ✕ (U+2715, MULTIPLICATION X, a dingbat), ☓ (U+2613, saltire), ✘ (U+2718, heavy ballot x) and ❌ (U+274C, cross mark).

Cross or dot by country

NIST’s SI guide prefers × between numbers in the United States, where the dot is the decimal marker. Where the comma is the decimal marker, it says the half-high dot is the preferred sign for multiplying numbers, though NIST still prefers × for values with units.

Other uses

In vector algebra × is the cross product; Miller dates it to Gibbs’s Vector Analysis by E. B. Wilson (1902), and Unicode gives it its own character, ⨯ (U+2A2F). In the Z notation of computing, Unicode notes, × is the Cartesian product.