Given : The addition 21.4 + 15 + 17.17 + 4.003 by the rules for significant figures.
Solution: According to given numbers, let us count number of significant figures in each of the given numbers.
21.4 has three significant figures.
15 has two significant figures.
17.17 has four significant figures.
4.003 has four significant figures.
We have to round the final answer to the nearest tens place because 15 has only accurate to the ones place.
We can see that other numbers are accurate to the tenths, hundredths and thousandths places, respectively.
Let us add them as usually first,
21.4 + 15 + 17.17 + 4.003.
It gives 57.573.
Now, we need to round it to the ones place.
We get 58 as the final answer.
