One of those is in time keeping, in which many clocks use the classical ... to correspond to Roman numerals. Blue, green, red and yellow are chosen to represent 1, 5, 10, and 50, or I, V, X ...
You may have seen Roman numerals on clocks and on TV or film credits ... 7 can be partitioned further into 5 and two 1s. These values have Roman numerals. Therefore, 77 is written as LXXVII ...