Across
1
Single numeral from 0 to 9
4
Power to which a number is raised
5
The number representing nothing
7
Result of addition
10
Part of a line with two endpoints
11
Mathematical statement of equality
13
Steepness of a line
Down
2
Collection of distinct elements
3
Math using letters for unknown values
6
Value that does not change
8
Three-sided polygon
9
Proven mathematical statement
12
Repeated addition