Crossword time! :)

12345678
Across
  1. 3. the letter which replaces the digit is called
  2. 5. the numbers 0,and all the natural numbers are known as ____numbers
  3. 6. the numbers 1,2,3,4,.... are known as ____ numbers
  4. 8. subtract the smallest value from the largest value
Down
  1. 1. _____ can also be written as 502sa
  2. 2. rational numbers are always in ____ form
  3. 4. one or more outcomes of an experiment make an
  4. 5. the difference between the upper class limit and lower class limit of a class interval is called
  5. 7. the expression on the left hand side of the equality sign is