555

What would you like about 555? Here are quick math notes you can use for exams, plus a couple of quick practice prompts.

Quick facts about 555 (decimal):

• 555 = 3 × 5 × 37 (prime factorization).
• Palindrome: reads the same forward and backward.
• Divisible by 3 and by 5 -> divisible by 15. Quotient: 555 ÷ 15 = 37.
• Number of divisors: (1+1)(1+1)(1+1) = 8.
• Sum of divisors (including itself): 912; sum of proper divisors: 912 − 555 = 357.
• In Roman numerals: DLV.
• Binary: 1000101011₂.
• Hexadecimal: 0x22B.

Quick exam-style practice:

• Question 1: Verify the divisibility by 15 and find the quotient. Answer: 555 ÷ 15 = 37.
• Question 2: Find the sum of all divisors of 555. Answer: 912.
• Question 3: Write 555 in binary and hex. Answer: Binary 1000101011₂, Hex 0x22B.
• Question 4: How many distinct divisors does 555 have? Answer: 8.
• Question 5 (optional): Convert 555 to base 8. Answer: 853₈.

If you want, I can tailor a short practice set to a specific course (math, number theory, or electronics with 555 timer) or convert 555 into other bases.