text: This phrase is used in business, not in Math.  It is used to illustrate good mergers.  When a peanut butter company and a jelly company combine you could get a 2 + 2 = 5 situtation.  The combination is logical and useful to each other.\n\nBut if the peanut butter company and a bullet manufacturer combined it would only be 2 + 2 = 4.  There is no mutual benefit.