555

Do you mean:

• (a) the number 555 (math properties and quick practice), or
• (b) the 555 timer IC (electronics) and its formulas?

If you want a quick math rundown now:

• Prime factorization: 555 = 3 × 5 × 37
• Number of divisors: 8
• Divisors: 1, 3, 5, 15, 37, 111, 185, 555
• Digit sum: 5+5+5 = 15 (divisible by 3 and 5)
• Palindrome: yes (reads the same forwards/backwards)
• Binary: 1000101011
• Hex: 0x22B

Tell me which you’re after, and I can tailor practice questions or explanations.