In digital design, a 16:1 multiplexer (mux) can be implemented using a combination of lower-order multiplexers, typically 4:1 muxes. The idea is to use the smaller muxes to build up to the desired larger mux. Assuming you have 4 inputs (A, B, C, D) and you want to select one of these inputs using a 16:1 mux (S0, S1, S2, S3 are the select lines),The output of this final 16:1 mux will be selected based on the four select lines (S0, S1, S2, S3), and the selected input will be passed through the hierarchy of 4:1 muxes.