Riley Darbonne Puzzle

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Across
  1. 1. a measure of the quantity of matter within an object
  2. 5. a measure of space
  3. 7. a system used to write very big and very small numbers
  4. 8. previously agreed on quantities used to report experimental measurements
Down
  1. 1. the si standard unit of length
  2. 2. the si standard unit of mass
  3. 3. a number that represents the number of times a term is multiplied by itself
  4. 4. the most convenient system of unit for science measurements
  5. 6. the si standard unit of time