Explain the Working of Frequency Division?

A frequency divider able to be constructed from J-K flip-flops by taking the output of one cell to the clock input of the next and the J and K inputs of each flip-flop are set to 1 to produce a toggle at each cycle of the clock input.

For every two toggles of the first cell a toggle is produced in the second cell thus its output is at half the frequency of the first and the output of the fourth cell is 1/16 the clock frequency. The similar device is useful as a binary counter.