Across
1
Corner point of a polygon
2
U-shaped curve of a quadratic function
3
Exact correspondence on both sides
4
Single numeral from 0 to 9
6
Symbol representing unknown value
Down
2
Number greater than zero
3
Rectangle with four equal sides
5
The number representing nothing
7
Round shape with all points equidistant
8
Result of multiplication
9
Number less than zero