Lupin spent the unhappiest hours of his life at that time. He doubted himself. He wondered whether his existence would be buried for good in the horror of a jail. Had he not made a mistake in his calculations?
The issue with the spacecraft carrying this radioactive substance was that if the scientists had gotten their calculations wrong and had crash-landed on Earth, everybody on the planet would have been exposed to the radiation.
I would recommend that you write between, let's say 160 and 200. Below 160, then there might be a chance that you will be under 150, if you miss-count.