555

Nice—would you like help with something specific about the number 555, or is this just a quick practice prompt? Here are some fast math notes and a small practice set you can use right away.

Quick facts about 555

• Decimal: 555
• Prime factorization: 555 = 3 × 5 × 37
• Divisible by: 3, 5, and 15 (but not by 9 or 7)
• Digital root: 5+5+5 = 15 → 1+5 = 6 (digital root = 6)
• Roman numeral: DLV
• Binary: 1000101011
• Hex: 0x22B
• Base-7: 1422_7

Short practice

1. Confirm the factorization: 555 = 3 × 5 × 37.
2. Is 555 divisible by 9? Why or why not?
3. Convert 555 to base 7: what is 555 in base 7? (Answer: 1422_7)
4. Write 555 in binary: (Answer: 1000101011)
5. How many positive divisors does 555 have? (Hint: If 555 = p^1 q^1 r^1, then number of divisors = (1+1)(1+1)(1+1) = 8)

If you want, I can tailor more problems to a specific course (e.g., number theory, algebra, or basics of discrete math) or turn this into a mini-study plan for your exam. What topic should we focus on?