555

Do you mean the number 555, or the 555 timer IC, or something else? Here are quick notes you can use for exams in math and electronics. Pick a focus and I can tailor more practice.

Math (555 as a number)

• Prime factorization: 555 = 3 × 5 × 37
• Divisors: 1, 3, 5, 15, 37, 111, 185, 555
• Digit sum: 5 + 5 + 5 = 15 → divisible by 3 and 5
• Base conversions:
  • Binary: 555 = 1000101011₂
  • Octal: 555 = 1053₈
  • Hexadecimal: 555 = 0x22B
• Roman numeral: DLV (500 + 50 + 5)

Electronics (555 timer IC)

• Pinout (DIP-8): 1 GND, 2 Trigger, 3 Output, 4 Reset, 5 Control Voltage, 6 Threshold, 7 Discharge, 8 Vcc
• Modes:
  • Monostable: one-shot pulse
    • Pulse width: t = 1.1 × R × C
  • Astable: continuous pulses
    • Frequency: f ≈ 1.44 / [(RA + 2RB) × C]
    • High time: tHIGH ≈ 0.693 × (RA + RB) × C
    • Low time: tLOW ≈ 0.693 × RB × C
• Common uses: timers, oscillators, PWM, debouncing, delays

If you want, I can:

• Factor 555 and give you all divisors with a quick check
• Convert 555 to any base you need or check divisibility
• Design a quick monostable/astable circuit example with given R and C
• Create a few practice exam problems with solutions

Which area should I focus on? Or do you want all three with solved examples?