SUMMER HOLIDAY PUZZLE

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Across
  1. 3. a flat surface which extends infinitely in all
  2. 6. forever in one direction
  3. 7. The equality of two ratios
  4. 10. A and B is called
  5. 11. A mathematical operation, written as bn, involving two numbers, the base b and the exponent or power n, and pronounced as "b raised to the power of n"
  6. 13. The number set {1,2,3,...} is called
  7. 14. The number set {...,-2,-1,0,1,2,3,...} is called
  8. 18. made by a piece of
  9. 19. A number that can be expressed as the quotient or fraction p/q of two integers.
Down
  1. 1. The number set {0,1,2,3,...} is called
  2. 2. The distance from zero that a number is on the number line, without considering direction.
  3. 4. Let a and b be the think of the same quantities. a/b is called
  4. 5. Let A and B be two different points on a line. The set of these two points and all points lying
  5. 8. Angle has a measure that lies between 90 degree and 180 degree
  6. 9. In a fraction p/q, what q is called
  7. 12. Angle has a measure below 90 degree
  8. 15. In a fraction p/q, what p is called
  9. 16. a statement that asserts the equality of two expressions, which are connected by the equals sign "=".
  10. 17. Each dot on a paper made by a pencil or on a
  11. 19. A straight line that begins at a certain point and