Test

2. The n-th root a number.
3. A statement that appears to contradict itself.
5. Pairs of numbers for which the sum of the divisors of one number equals the other number.
10. Exactly the same. Identical in regard to size and shape.
11. A rectangular array of numbers.
14. A number that is the sum of its divisors (excluding the number itself).
16. A line which crosses two or more parallel or nonparallel lines in a plane.
17. The point towards which a series or function converges.
19. A device used to measure the dimensions of an object.
20. Prime numbers that are one more than a power of 2.

1. A mathematical structure consisting of a set together with an operation.
4. A set of points that lie on a circle.
6. A step by step procedure by which an operation can be carried out.
7. A number that will divide into another number exactly.
8. An equality that remains true regardless of the values of any variables that appear within it.
9. Intersection point of two plane.
12. The four divisions on a coordinate graph.
13. a physical quantity having magnitude and direction.
15. A plane curve having two centres.
18. To divide into two equal sections.