Across
1
Exact correspondence on both sides
5
Three-sided polygon
9
Rectangular array of numbers
10
The number representing nothing
11
Number with digits after a point
12
U-shaped curve of a quadratic function
13
Split into equal parts
Down
2
Closed shape with straight sides
3
Value that does not change
4
Amount of space an object occupies
6
Number greater than zero
7
Single numeral from 0 to 9
8
Number less than zero