Across
1
Difference between highest and lowest values
5
Symbol representing unknown value
8
Total distance around a shape
9
Sum divided by count
Down
2
The number representing nothing
3
Split into equal parts
4
Closed shape with straight sides
6
Rectangle with four equal sides
7
Round shape with all points equidistant
8
Result of raising a number to an exponent
10
Divisible by two