Explain why 323.202 is least
than 323.21 even though 202 is grater than 21

It is less than 324.21, because as you can see, all the numbers are equal until you get to the 0 & 1, and 1 is greater than 0

323.21 is greater than 323.202 because of the placement in tenths, hundredths and thousandths, written out as a fraction it would be:
202/1000 versus 21/100
which one is bigger? the 21/100, so its of greater value