Abacteria culture begins with eight bacteria which triple in size every week. how many bacteria exist in the culture after four weeks

Well, you would have to multiply 8 by whatever factorial of 3, in this case 4 for the number of weeks
The equation is 8 x 3^4 which equals 648

My only thing is that they only triple in SIZE, and not multiply (as in make more of themselves) so technically speaking, there would still be 8 bacteria, just much bigger