Across
1
Steepness of a line
5
Single numeral from 0 to 9
6
Rectangular array of numbers
7
The number representing nothing
8
Number with digits after a point
9
Value that does not change
10
Divisible by two
11
Difference between highest and lowest values
Down
1
Rectangle with four equal sides
2
Total distance around a shape
3
Line crossing from corner to corner
4
Symbol representing unknown value