555

Do you mean the number 555, the 555 timer IC (electronics), or something else? Which subject are you prepping for?

If you want a quick math warm-up using 555, here are a few bite-sized items:

• Factorization: 555 = 3 × 5 × 37
• Divisibility: divisible by 3 and 5 (not by 9)
• Binary and hex: 555 = 1000101011₂ = 0x22B
• Square: 555² = 308,025
• Base 7 representation: 555 = 1422₇

Would you like a 5-question mini-quiz, or should I tailor it to a specific topic (e.g., modular arithmetic, base conversions, etc.)? If you meant the 555 timer, I can give you quick notes and sample problems for astable/monostable modes.