Play begins when a player places a bet by putting chips in the betting boxes of his choice on the roulette table (either single numbers, complete rows, or colours) before the dealer spins the wheel. In many casinos, it is possible to place bets while the roulette wheel is spinning. When placing bets on multiple numbers, the player can place their chips so as to cover multiple betting boxes. In effect, this is the same as placing some fraction of a bet (a half or a quarter) on each number.
( European roulette - betting boxes. Source: screenshot of European roulette Európskej Rulety from Play 'n' GO)