Number of MUX required for Cache Mapping
A multiplexer can output only a single bit on output line.
So, to output one complete tag to the comparator ,

Number of multiplexers required = Number of bits in the tag. (say T)

If there are k lines in one set, then number of tags to output = K,

thus ,

number of multiplexers required = Number of lines in one set (K) x Number of bits in the tag(T).

TOTAL MUX REQUIRED = K*T