Across
1
Symbol representing unknown value
5
Parts per hundred
6
Reference line in a graph
8
Rectangle with four equal sides
12
Number less than zero
Down
2
Space between two intersecting lines
3
Single numeral from 0 to 9
4
Line touching circle at one point
7
Value that does not change
9
Difference between highest and lowest values
10
Proven mathematical statement
11
Sum divided by count
13
Longest side of a right triangle