555

Do you want help with math, electronics (555 timer), or something else involving 555? Here are quick angles to choose from:

• Math facts about 555:

  • Prime factorization: 555 = 3 × 5 × 37
  • Divisible by 3 and 5; not by 7 or 11
  • Factors: 1, 3, 5, 15, 37, 111, 185, 555

• Roman numerals: 555 = DLV

• Electronics (555 timer): In astable mode, f ≈ 1 / [0.693 (RA + 2 RB) C] (also written f = 1.44 / ((RA + 2 RB) C)).

  • t_high = 0.693 (RA + RB) C
  • t_low = 0.693 RB C

If you tell me which topic you want, I can give a quick example problem or a mini-quiz.