A switching function is said to be linearly separable if the weighted sum of the input variables of the logical element realizing the function equals or exceeds a threshold. The weights and threshold are all real numbers. All switching functions are not linearly separable. A test and realization procedure for linearly separable switching functions using the decimal number representation of the input variable combinations only is presented here. The test process uses the 2-asummability property of linearly separable switching functions and is usable for switching functions of eight or lesser number of variables. A slide-rule device is described where the test can be mechanically done promptly. The realization technique is iterative and gives integral solutions directly. The method is straightforward and is very useful, particularly for a small number of variables.