Across
1
Difference between highest and lowest values
5
The number representing nothing
6
Split into equal parts
8
Mathematical rule or equation
9
Math using letters for unknown values
12
Exact correspondence on both sides
15
Reference line in a graph
Down
2
Amount of space an object occupies
3
Divisible by two
4
U-shaped curve of a quadratic function
7
Part of a line with two endpoints
10
Number with digits after a point
11
Symbol representing unknown value
13
Single numeral from 0 to 9
14
Number greater than zero