555

Do you mean the number 555 (math) or the 555 timer IC (electronics)? If you meant something else, tell me.

If you meant 555 in math:

• Prime factorization: 555 = 3 × 5 × 37
• Digits sum: 5+5+5 = 15
• Roman numeral: DLV
• Binary: 555 = 1000101011₂
• Hexadecimal: 0x22B
• Base-7 representation: 555₁₀ = 1422₇
• Quick divisors: 1, 3, 5, 15, 37, 111, 185, 555

If you meant the 555 timer IC (electronics):

• Pinout (8-pin DIP): 1 GND, 2 Trigger, 3 Output, 4 Reset, 5 Control Voltage, 6 Threshold, 7 Discharge, 8 Vcc
• Modes:
  • Astable (oscillator): f = 1.44 / ((R_A + 2R_B) C). t_high = 0.693 (R_A + R_B) C. t_low = 0.693 R_B C.
  • Monostable (one-shot): t = 1.1 R C (triggered by a negative pulse on Trigger).
  • Bistable: no RC timing; uses external set/reset.
• Typical supply: ~4.5 V to 15 V
• Common applications: LED flasher, timers, PWM, debouncing, pulse generation

Which one should I dive into? I can give a quick worked example if you want.