555

Here are quick notes and a small practice set around the number 555 for exam prep.

Key facts

• Decimal factorization: 555 = 3 × 5 × 37
• Divisible by: 3, 5, 15 (and thus by 1, 3, 5, 15, 37, 111, 185, 555)
• Not divisible by: 9, 7, 11
• Roman numeral: DLV
• Binary: 1000101011
• Hexadecimal: 0x22B

Practice questions

1. Is 555 divisible by 9? Explain briefly.
2. Find gcd(555, 270).
3. Compute lcm(555, 14).
4. Convert 555 to Roman numerals (confirm your answer).
5. Write 555 in binary (show the steps).

Suggested answers

1. No. Sum of digits is 15, which is not a multiple of 9.
2. gcd(555, 270) = 15.
3. gcd(555, 14) = 1, so lcm = 555 × 14 = 7770.
4. 555 = 3 × 5 × 37, so Roman numeral is DLV.
5. Binary: 1000101011.

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