OICC Press International Journal of Mathematical Modelling & Computations 2228-6233 6 3 2016 07 01 NUMERICAL SOLUTION OF DELAY INTEGRAL EQUATIONS BY USING BLOCK PULSE FUNCTIONS ARISES IN BIOLOGICAL SCIENCES 221 231 EN M. Nouri Department of Mathematics, South Tehran Branch, Islamic Azad University, Tehran, Iran K. Maleknejad Department of Mathematics, Iran University of Science and Technology, Narmak, Tehran, Iran Journal Article 2016 07 01 This article proposes a direct method for solving three types of integral equations with time delay. By using operational matrix of integration, integral equations can be reduced to a linear lower triangular system which can be directly solved by forward substitution. Numerical examples shows that the proposed scheme have a suitable degree of accuracy.