Across
1
Single numeral from 0 to 9
3
Closed shape with straight sides
6
Proven mathematical statement
9
Difference between highest and lowest values
10
Number divisible only by 1 and itself
11
System of ordered marks for measuring
Down
2
Part of a line with two endpoints
4
Comparison of two quantities
5
Longest side of a right triangle
7
Three-sided polygon
8
Number that divides evenly into another
12
Total distance around a shape
13
Steepness of a line