Explanation: A decade counter, also known as a divide-by-ten counter, is a fundamental digital IC in electronics. Its primary function is to count input pulses and produce an output pulse after every ten input pulses have been received. Effectively, it divides the input frequency by ten. This characteristic makes it valuable in frequency division circuits, time-base generation, and in various digital display systems where counting in decimal (base-10) is required. Option A is incorrect because decoding for a seven-segment display is the function of a decoder IC, which typically takes the output of a counter and converts it for display. Option C is incorrect as it describes a frequency multiplier, which is the opposite of a counter's divide-by-ten function. Option D is incorrect because adding numbers is the function of an adder IC, not a simple counter.