FORMULA TO PERFORM A MATHEMATICAL EQUATION ON A SET OF NUMBERS WITHIN A STRING OF NUMBERS, THEN REPLACE THE SET OF NUMBERS WITH THE MATHEMATICAL RESULT IN THE SAME STRING OF NUMBERS (EXAMPLE: 123456 STRING OF NUMBERS, & MATHEMATICALLY REDUCE THE MIDDLE NUMBER OF 34 BY 1, THEN REPLACE THE ANSWER TO THE ORIGINAL STRING RESULTING IN 123356)
Solved by D. J. in 30 mins