The numbers 23.982 and 3.4687 are both approximate and correct only to their last digits. Find their difference and state how many figures in the result are trustworthy.

23.982-3.4687 = 20.513, which contains 5 significant figures.

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Attn: Since the result of addition or subtraction should be no more accurate than the least accurate one.

## Comments

Because both numbers are with 5 significant figures, then result should be with 5 significant and trustworthy figures too. Only my question is, do we have to accompany the result with the relative error of the round-off?