Two things you could measure is a person's height and the speed needed to reach the planet Mars. The person's height can be measured with a low level of precision, which means we don't need to be that accurate. We could say "that person is about 6 feet tall" and whoever is listening would get a sense of their height. In contrast, we need high precision for a rocket speed to Mars because getting this figure wrong would likely cause disaster down the road. Very complicated mathematics is essential to make sure we hit the target required in space.
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Problem 2
As mentioned, we need high precision when it comes to anything dealing with space travel. If the calculations are wrong, then the spacecraft could crash somehow. As one example where things went wrong, engineers used the wrong values and the Mars lander ended up crashing into the planet rather than landing safely. The high cost of such space exploration missions means that it's very crucial to get precise values as much as possible, to as accurate as possible. Things like discussing a person's height isn't that essential to be very precise as we can just relay estimates to whoever we're talking to. This informal setting doesn't demand as much accuracy compared to something like a rocket launch.
