555

Not sure what you want with “555.” Do you want math prep related to the number, or something else (e.g., Thai slang, a quick problem set, etc.)?

If you’re studying math, here are a few quick notes and problems you can use in exams:

• Factorization: 555 = 3 × 5 × 37
• Divisors: 1, 3, 5, 15, 37, 111, 185, 555 (so 8 divisors)
• Sum of digits = 15, so divisible by 3 (and hence by 3, 5, 15, etc.)
• Quick problems:
  1. gcd(555, 420) = 15
  2. lcm(555, 420) = (555 × 420) / 15 = 15540
  3. Solve 555x ≡ 1 (mod 7): since 555 ≡ 2 (mod 7), 2x ≡ 1 (mod 7) → x ≡ 4 (mod 7)
  4. Express as product of primes: 555 = 3 × 5 × 37

Would you like more problems, or a different topic (calculus, linear algebra, statistics, etc.)?