Across
1
Rectangle with four equal sides
4
Symbol representing unknown value
5
Number divisible only by 1 and itself
6
System of ordered marks for measuring
7
Part of a line with two endpoints
12
The number representing nothing
Down
1
Steepness of a line
2
Repeated addition
3
Space between two intersecting lines
8
Round shape with all points equidistant
9
Mathematical statement of equality
10
Math using letters for unknown values
11
Difference between highest and lowest values
13
Longest side of a right triangle