This research discusses an alternative method to solve the value problem of internet Rate Return or the method to calculate the value of Internet Rate Return (IRR) and the desired returned rate by Bonds investor. There were several methods to solve the calculation of IRR, such as Interpolation Method, Using the Financial Table, Trial and Error Method, and Using IRR Function in Excel Software. In this paper, the author will present the Application of Numerical Mathematic. There are a number of methods in Numerical Mathematic, but the most popular one is Netwon Raphos Method. In this method, the case needs to be transferred into the NPV Equation or Bonds Equation either in the Case of Premium or Disconto Bonds. Then a Polinomial equation in term of f(x)is created. Iteration is conducted until the eror is minimum. In terms of the result, this method gives the same outcome as the methods menationed above.there is only an approximation of 4 digits in decimals in the result. Using this method, there is still difference in the outcome, but it is not significant. Keywords: Internal rate return, Interpolation Method Numerical Mathematic, NewtonRaphson Method, NVP equation,Polinominal equation, Interation, Bonds, Approximation