555

Could you clarify what you want about 555? Here are common interpretations:

• As a number: 555 = 3 × 5 × 37; a repdigit in base 10.
• Roman numerals: 555 = DLV.
• 555 timer IC: a versatile timer used in astable/monostable/bistable modes (basic formulas: frequency/pulse width, etc.).
• Color code: #555555 is a medium gray (RGB all equal to 85).

Which one would you like help with? Or tell me the exact context (math problem, electronics, color, etc.).