Across
1
The number representing nothing
3
Math using letters for unknown values
5
Reference line in a graph
8
Collection of distinct elements
9
Result of multiplication
10
Number less than zero
11
Longest side of a right triangle
Down
2
Rectangle with four equal sides
4
Number with digits after a point
5
Part of a circle's circumference
6
Difference between highest and lowest values
7
System of ordered marks for measuring
12
Space between two intersecting lines