Optimal bundle pricing for homogeneous items

The tone production system for an electronic musical instrument comprises depressed key detection means for outputting pulses at a timing corresponding to a key depressed by time division timings assigned to each note, a shift register for shifting successively said pulses outputted from said depressed key detecting means in synchronism with said time division timing, key data forming means for taking out each output pulse of predetermined plural stages of said shift register in accordance with a desired type of chord, musical tone production means for producing each of plural musical tone signals of notes corresponding to pulse generation timings in accordance with each pulse taken out by said key data forming means.