The decade of the 1950s. / Temperatures from 50 to 59 degrees.

An Internet connection nominally capable of download speeds up to 56 kbit/s (56,000 bits per second).

(humorous, Canada, US) This is my guess.

simple past tense and past participle of 5150

plural of 527

(sports) The act of spinning 540 degrees in the air, making 1½ turns.

(singular only) The list published annually by Fortune magazine of the 500 United States companies with the highest revenue. / (plural only) Collectively, the members of that list.

(physics) The naturally-occurring radioactive isotope of vanadium, ⁵⁰₂₃V, having twenty-three protons and twenty-seven neutrons; its half-life is 1.5 x 10¹⁷ years

plural of 50-50

plural of Fortune 500