555

Do you want to review 555 in a particular context? Here are the common exam-related interpretations:

• Number theory (pure math)

  • 555 = 3 × 5 × 37
  • Divisible by 3, 5, and 15
  • Divisors: 1, 3, 5, 15, 37, 111, 185, 555
  • In Roman numerals: DLV
  • In binary: 1000101011
  • In words: five hundred fifty-five

• Electronics (555 timer IC)

  • Modes: astable (oscillator), monostable (one-shot), bistable
  • Key formulas (typical values, for design):
    • Astable frequency f ≈ 1.44 / [(RA + 2 RB) C]
    • Duty cycle D = (RA + RB) / (RA + 2 RB)
    • Monostable pulse width t ≈ 1.1 × R × C
  • Pins (classic 8-pin): 1 GND, 2 Trigger, 3 Output, 4 Reset, 5 Control, 6 Threshold, 7 Discharge, Vcc
  • Supply: ~4.5–16 V

• Other (dates, sequences)

  • 5/5/5 as a date or repeating sequence

Which of these would you like to dive into, or do you have a different context for 555? I can give a quick problem or a deeper walkthrough.