and 613=87×7+4, 7=4+3, 4=3+1, so 1=4-3=(613-87×7)-(7-4)=613-87×7-7+4=
=613-88×7+(613-87×7)=2×613-175×7=1
So, for example, 621=621×1=621(2×613-175×7)=1242×613-108675×7
Once again I fail to understand what you are getting at. Do you think these calculations have anything to do with the fact that 613 + 7 = 620? It is very simple addition... No division, no multiplication, no factors, no prime numbers.
Do you understand the basic addition operator? It is one of the simplest arithmetic operators we know {although subtraction is similar}. There are applications of Gematria which involve multiplication such as the idea that Chai, the numerical value of 18, is a lucky number so people often donate money in multiples of 18, for instance $18, $36, $72, $90, $180, etc...