555

Not sure what you mean by 555. Do you want:

• math problems about the number 555, or
• help with the 555 timer IC, or
• just that you’re laughing (555 is used as "hahaha" in Thai)?

If you meant the number 555, here are quick facts and a mini-practice set:

Quick facts

• Factorization: 555 = 3 × 5 × 37
• Divisors: 1, 3, 5, 15, 37, 111, 185, 555
• Sum of all divisors: 912 (so the sum of proper divisors is 912 − 555 = 357)
• Harshad number in base 10: 555 ÷ (5+5+5) = 37
• Binary: 1000101011
• Hexadecimal: 0x22B
• Roman numeral: DLV

Mini-quiz (answers included)

1. Is 555 prime? No. (It has factors 3, 5, and 37)
2. What is 555 in roman numerals? DLV
3. What is the sum of its divisors? 912
4. List a few divisors of 555. 1, 3, 5, 15, 37, 111, 185, 555
5. Is 555 a Harshad number in base 10? Yes (555 ÷ 15 = 37)
6. What is 555 in hexadecimal? 0x22B

If you’d like, I can tailor more problems to your course (e.g., number theory, discrete math) or switch to the 555 timer IC with explanations and typical exam-style questions. Let me know what you’re studying.