555

Not sure what you want with “555.” Here are quick math-focused facts you can use right away, in case you’re prepping for an exam:

• Factorization: 555 = 3 × 5 × 37
• Also: 555 = 5 × 111 = 5 × (3 × 37)
• Divisibility: sum of digits = 15, so divisible by 3 and 5; hence by 15. 555/15 = 37
• Palindrome / repdigit: digits are all the same
• Roman numeral: DLV
• Binary: 1000101011
• Hexadecimal: 0x22B
• Angles/time: 555° ≡ 195° (mod 360); 555 seconds = 9 minutes 15 seconds
• Harshad (Niven) number in base 10 (divisible by sum of digits)

Would you like me to turn this into a practice problem, or help with a specific topic (factorization, divisibility rules, base conversions, etc.)? If you meant something else (e.g., the 555 timer IC), tell me and I’ll tailor it.