555

Do you mean the number 555, or were you just laughing? If you want a quick math note, here are some handy facts about 555:

• Decimal: 555
• Prime factorization: 3 × 5 × 37
• Divisibility: divisible by 3, 5, and 15 (since digits sum to 15 and last digit is 5)
• GCD example: gcd(555, 600) = 15
• Binary: 1000101011₂
• Hex: 0x22B
• Roman numeral: DLV
• Palindrome: yes (reads the same forwards and backwards)
• Base conversions:
  • Base 3: 202120₃
  • Base 16: 22B₁₆
• Square: 555² = 308,025

If you want, I can tailor this to a specific exam topic (number theory, modular arithmetic, conversions, etc.) or give you a quick practice problem. What would you prefer?