90   Numerical and graphical method.   Numerical analysis

91   Interpolation and approximation.   Numerical solutions of algebraic-differential & integral equations.   Numerical linear algebra.   Finite element method

92   Difference equations.  Calculus of finite differences.  Difference-differential equations

93   Linear programming.   Non-linear programming

94   Nomography and curve fitting

95   Calculation and integration devices

96   Nonlinear computation.   Functional equations

97   Computational differential equations