555

Not sure what you want with “555.” Do you want a quick problem or explanation involving the number, or is 555 referring to something else (like the 555 timer in electronics)?

If you’d like, here are a few quick math-oriented things about 555 to get started:

• Factorization and divisors: 555 = 3 × 5 × 37. Divisors are 1, 3, 5, 15, 37, 111, 185, 555 (8 divisors).
• Base representations: 555 in binary is 1000101011_2; in hexadecimal it is 0x22B.
• Roman numeral: DLV.
• Digit sum and simple mod: sum of digits is 15; 555 mod 9 = 6; 555 mod 5 = 0.

If you want exam-style practice, I can generate a short set of problems (with solutions) on number theory, modular arithmetic, or base conversions using 555. Or tell me the subject/topic you’re studying and I’ll tailor it.