In series 6,4,1,2,2,8,7,4,2,1,5,3,8,6,2,1,7,1,4,1,3,2,8,7,6, how many pairs of successive numbers have a difference of 1 each?
6,4,1,2,2,8,7,4,2,1,5,3,8,6,2,1,7,1,4,1,3,2,8,7,6 ** Six - 8,7/2,1/2,1/3,2/ 8,7/ 7,6 **