This table courtesy of Poker770 helps about finding out your chances of completing your hand according to your number of 'Outs'.

The 'Outs' are the cards that could improve your hand. To count 'Outs', players need to confront their 'outs' with the number of remaining cards as in the number of possibilities that the hand won't improve. It is possible to stay in the competition and call if the percentage is higher than 10%.