Do anyone know the reason the values of standard 1% Tolerance Resistors were chosen the way they are? I need to choose some resistors to offset my A/D and was thinking about getting excel to crunch the numbers. The values seem to increase at approximately 2.5% the previous value but no quite. Do anyone know of any programs that select resistor values for voltage dividers and op-amp gains other than brute force guess and select? - -Mark