maths terminology

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Across
  1. 1. A pair of numbers that satisfies an equation (5 letters)
  2. 3. The mathematical representation of a quantity with magnitude and direction (5 letters)
  3. 6. The study of numbers and their properties (9 letters)
  4. 7. The branch of mathematics that deals with the properties of shapes and figures (7 letters)
  5. 8. The sum of a series of numbers divided by the count of numbers (5 letters)
Down
  1. 2. A line that touches a curve at a single point (6 letters)
  2. 4. A number that can be expressed as a fraction (6 letters)
  3. 5. The ratio of the circumference of a circle to its diameter (4 letters)