|Roughly speaking adding two 32 bit numbers requires 32 Boolean gates.
Why do you need millions of transistors? I know there is also substraction, division, multiplying, comparison etc. Some operations probably require way more Boolean gates than the number of bits the numbers involved in the operation are made of.
Also my guess is there is a comparison based mathematical operation type selector that directs the bits to the correct area on the processor pill. Still it’s difficult to imagine where millions of transistors go.
If I think about it more I get it, this is just Alu. There is also non mathematical stuff that needs to be taken care of as well.