Complex sentence: The generation of random numbers has many uses (mostly in statistics, for random sampling, and simulation); originally researchers needing random numbers would generate them through various means-dice, cards, roulette wheels... or use existing random number tables.
Split into simpler sentences: The generation of random numbers has many uses (mostly in statistics, for random sampling, and simulation). Before modern computing, researchers requiring random numbers would either generate them through various means (dice, cards, roulette wheels, etc.) or use existing random number tables.