555

Not sure what you need with 555. Here are a few quick angles—pick one and I’ll go deeper:

• Math number 555

  • Prime factorization: 555 = 3 × 5 × 37
  • Number of divisors: (1+1)(1+1)(1+1) = 8
  • Binary: 1000101011
  • Roman numeral: DLV

• 555 timer IC (electronics)

  • Common configurations: monostable, astable
  • Astable frequency: f ≈ 1.44 / [(R1 + 2R2) C]
  • Monostable pulse width: t ≈ 1.1 R C

• If you’re after exam-style practice, I can generate a quick problem set on whichever topic you choose.

Which one would you like? Or tell me the subject and I’ll tailor it.