multiply

The motives to refuse obedience to government are many and strong ; impunity will multiply and enforce them

when you multiply 3 by 7, you get 21; he multiplied several numbers

[The researchers] noticed many of their pieces of [plastic marine] debris sported surface pits around two microns across.[…]Closer examination showed that some of these pits did, indeed, contain bacteria, and that in several cases these bacteria were dividing and thus, by the perverse arithmetic of biological terminology, multiplying.

He had been multiplying, but it occurred to him he needed to resolve the exponents, first.

This follows a similar process, counters having to be removed and replaced at each stage of the remaining part of the calculation except the final one, where 2 multiplies 3 to give 6.