Pseudo-random number generators (PRNGs) are considered as mathematical algorithms, that produce sequences of random numbers. They can be used in many applications such as operation research, statistics and cryptography which require random numbers. For this purpose, modifications have been applied to Blum-Blum-Shub(BBS) PRNG to increase the bit-sequence while lower number of iterations is required to achieve better randomness. Besides that, randomness hypothesis test is performed to study the randomness behavior, and our results indicate that all algorithms have fulfilled the randomness test except the cubic BBS algorithm.