9×10

9×10 is a mathematical expression that denotes the product of the integers 9 and 10. In base-10 arithmetic, the result is 90, making 9×10 a familiar entry in the multiplication table. Because multiplication is commutative, 9×10 equals 10×9. The product can be factored as 2 × 3^2 × 5 and, in decimal notation, the result is 90; in binary it is 1011010, and in Roman numerals it is XC.

In addition to arithmetic, 9×10 is commonly encountered as a dimension or grid size, such as a 9-by-10 rectangle that contains 90 unit squares. It is also used to describe the dimensions of matrices, images, or game boards.

Historically, the fact that 9 times 10 equals 90 has been part of multiplication tables developed across many cultures to facilitate mental calculation and commerce. The expression remains a standard example in elementary mathematics for illustrating basic multiplication, properties of numbers, and conversions between numeral systems.