6x9

6x9 is a notation used to express either a two-dimensional dimension described as six by nine, or the arithmetic product of the numbers six and nine. In mathematics, 6 × 9 equals 54 in base-10 arithmetic.

In practical contexts, 6x9 is commonly seen as a size specification. For example, 6x9 inches is a standard trim size for many trade paperback books and for various photographic prints, while 6x9 centimeters is used for some camera negatives and print formats.

As an aspect ratio, 6:9 simplifies to 2:3, making 6x9 images compatible with many 2x3 photo frames and printing templates.

In popular culture, the phrase has a notable joke: in The Hitchhiker's Guide to the Galaxy, six times nine equals 42 when calculated in base 13, illustrating how base systems can lead to different results.

Overall, 6x9 is a versatile descriptor used across mathematics, publishing, photography, and design, reflecting both a simple arithmetic product and common dimensional formats.