It means having more than one digit. In the context of decimal integers it means a number greater than 9.
A number
An array is a set of numbers that form some sort of regular arrangement. A linear array is a 1-dimensional array consisting of a row or a column of a set of numbers. A 2-dimensional array is a rectangular arrangement of numbers. And there are arrays with higher dimensions. The elements of an array need not be numbers: they could be variables, functions or expressions. In other words, it's a picture to describe a multiplication problem.
the digit before the decimal point in decimal notation, representing an integer less than ten.
what does key mean in math
a
about
Approximately
many
I do not know of such a word related to math(s)
the word by means 'times' or 'multiply'
The word at means the least