555

Do you want math-focused stuff about the number 555, or something else (e.g., 555 timer electronics)? Here are quick math facts and a few practice problems you can use in exam prep:

Quick facts about 555

• Prime factorization: 555 = 3 × 5 × 37
• Number of divisors: 8 (divisors are 1, 3, 5, 15, 37, 111, 185, 555)
• Sum of divisors: 912
• Digits: sum of digits = 15; product of digits = 125; digital root = 6
• Roman numeral: DLV
• Base representations:
  • Binary: 1000101011_2
  • Hexadecimal: 0x22B
  • Octal: 1053_8
  • Base-7: 5422_7
• It is a palindromic decimal number (reads the same forwards and backwards)

Short practice problems (with answers)

1. Factorization and divisors

   • Write the prime factorization and list all divisors.
   • Answer: 555 = 3 × 5 × 37; divisors as above.

2. Base conversion

   • Convert 555 to base 2, base 8, and base 16.
   • Answer: 2: 1000101011, 8: 1053, 16: 22B

3. Sum/product of digits

   • Compute sum and product of digits; also the digital root.
   • Answer: sum = 15, product = 125, digital root = 6

4. A quick number theory check

   • Is 555 divisible by 9? By 3? By 5?
   • Answer: Divisible by 3 and 5; not by 9.

If you want, tell me your exam topic (factoring, modular arithmetic, bases, etc.), and I can tailor a set of problems with solutions.