Across
1
The number representing nothing
2
Single numeral from 0 to 9
3
Closed shape with straight sides
6
U-shaped curve of a quadratic function
7
Rectangle with four equal sides
8
Mathematical statement of equality
9
Parts per hundred
Down
2
Line crossing from corner to corner
3
Lines that never intersect
4
Longest side of a right triangle
5
Middle value in an ordered dataset