<span>The precision of scientific calculations is limited by the measurement that's the least precise out of all the measurements used in the calculation. When considering significant figures, the last answer should have the least significant figures out of all the measurements that entered into account and were able to be done with the most significant figures that could be directly measured. So, as more precise we are in measurements, more precise can be the final answer to a scientific calculation.</span>
They do not have a distinct head and thorax but a fused version of the two called a cephalothorax. That's one of the major differences between insects and crustaceans, both being subgroups of arthropods.
