Across
1
The number representing nothing
4
Three-sided polygon
5
Power to which a number is raised
6
Collection of distinct elements
7
Result of addition
10
Rectangular array of numbers
11
Part of a line with two endpoints
Down
2
Value that does not change
3
Proven mathematical statement
6
Exact correspondence on both sides
8
Mathematical rule or equation
9
Amount of space an object occupies
12
Longest side of a right triangle
13
Sum divided by count