I numeri

12345678910
Across
  1. 3. A "perfect" number, it’s both the sum and product of its factors (1, 2, and 3).
  2. 4. The first natural number, and the only number with a single factor.
  3. 6. The highest single-digit number and the square of tre (3).
  4. 8. A number with a magic all its own, it’s often associated with luck or good fortune.
  5. 9. The number of suits in a standard deck of playing cards.
  6. 10. A number that often symbolizes completion or perfection, it's also the base of our modern decimal system.
Down
  1. 1. This number has the same digit in its square as it does in its cube.
  2. 2. The smallest and only even prime number.
  3. 5. This number lies between a square and a cube, and its Roman numeral is made up of two stacked circles.
  4. 7. The number of notes on a musical scale.