A multiplier with a feedback has the unique combination of the following properties: a wide range of multiplied frequencies (10:1 and wider); a large and easily variable scaling factor; it is independent of the input signal voltage shape or amplitude; it can operate with a variable input frequency; it is insensitive to stray frequency modulation of the input signal at frequencies above the effective modulating range; a possibility of direct multiplication of the difference of two frequencies, or even a linear combination of several frequencies; and a possibility of correcting the nonlinearity of transducers, if this nonlinearity is not too large. Thus, it meets virtually all the requirements which can be specified for a frequency multiplier intended for working in a frequency-digital measuring system.