555

If you meant the number 555, here are quick exam-ready notes and a few practice prompts.

Quick facts

• Decimal factorization: 555 = 3 × 5 × 37
• Divisibility: divisible by 3, 5, 15; not by 9, 7, or 11
• Digit sum: 5+5+5 = 15; digital root = 6
• Roman numeral: DLV
• Base conversions:
  • Binary: 1000101011₂
  • Octal: 1053₈
  • Hexadecimal: 0x22B
  • Base 9: 676₉

Practice problems (with quick solutions)

1. Prove the factorization 555 = 3 × 5 × 37.

   • 555 is divisible by 3 (sum of digits 15 is multiple of 3) → 555 / 3 = 185.
   • 185 is divisible by 5 → 185 / 5 = 37.
   • So 555 = 3 × 5 × 37.

2. What is 555 mod 7?

   • 7 × 79 = 553, so 555 ≡ 2 (mod 7).

3. Convert 555 to base 16.

   • 555 = 2×256 + 43 → 0x22B.

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