555

Do you want to work with 555 as a number (math) or the 555 timer IC (electronics)? Here are quick starters for both.

If you mean 555 as a number (math):

• Decimal: 555
• Roman numerals: DLV
• Prime factorization: 3 × 5 × 37
• Palindrome in base-10
• Base conversions (examples):
  • Binary: 1000101011
  • Octal: 1053
  • Hex: 0x22B
  • Base-6: 2323_6
  • Base-5: 4210_5
  • Base-3: 202120_3

If you mean the 555 timer IC (electronics):

• Pinout (common DIP): 1 GND, 2 Trigger, 3 Output, 4 Reset, 5 Control, 6 Threshold, 7 Discharge, 8 Vcc
• Modes:
  • Astable: frequency f ≈ 1.44 / ((RA + 2 RB) C)
  • Monostable: pulse width t ≈ 1.1 × R × C
• Quick example: monostable with R = 10 kΩ, C = 100 nF gives t ≈ 1.1 ms
  • Astable example: RA = RB = 1 kΩ, C = 1 μF gives f ≈ 1.44 / ((1k + 2×1k) × 1 μF) ≈ 480 Hz

Which direction would you like to go? If you share a specific target (problem to solve, base you want, or a circuit you’re building), I’ll tailor a concise solution.