555

Not sure what you want with 555. Do you want quick math facts, or a small practice set around this number, or something else? Here are some ready-to-use notes you can copy into an exam prep sheet:

• Prime factorization: 555 = 3 × 5 × 37
• Divisibility: divisible by 3 (sum of digits = 15) and by 5 (ends in 5); not divisible by 9
• Harshad (Niven) number: 555 ÷ (3+6+... wait) actually 3+5+5 = 13? No—sum of digits is 15, so 555 ÷ 15 = 37, yes it’s a Harshad number
• Other representations:
  • Binary: 555_10 = 1000101011_2
  • Hexadecimal: 0x22B
  • Roman numeral: DLV

Quick practice questions (optional):

• gcd(555, 1000) = ?
• Is 555 prime? (No)
• Express 555 as a product of primes (done above)
• Convert 555 to base 7: 1422_7

If you tell me the subject (algebra, number theory, combinatorics, etc.) or give me a problem, I’ll tailor a focused mini-quiz or step-by-step solution.