Answer:
So we have a measure in grams, we can start with something like:
143.523 grams.
Now we want this measurement to be precise to the nearest tenth of a gram.
The nearest tenth of a gram is the first digit after the decimal point, then the digits that come after this are not useful, because they are outside our precision range.
Then we must write our measurement as:
143.5 grams
Where the digit that came after the 5 was a 2, so we rounded down.