1. 2 \( \times \) 5
  2. (C) 3 \(\times\) 3 \(\times\) 3
  3. 23
  4. 2 \( \times \) 2 \( \times \) 2 \( \times \) 2 \( \times \) 5 \( \times \) 5 \( \times \) 5
  5. 2 \( \times \) 2 \( \times \) 2 \( \times \) 5 \( \times \) 5 \( \times \) 5
  6. 3 \(\times\) 19
  7. 2 \(\times\) 2 \(\times\) 2 \(\times\) 2 \(\times\) 2 \(\times\) 3
  8. 2 \(\times\) 7 \(\times\) 7
  9. 2100
  10. 2 \( \times \) 2 \( \times \) 3 \( \times \) 3 \( \times \) 11
  11. 133 is a prime number