Final answer:
To add 60.09 and 82.4, align the decimal points and add as usual. Since the original numbers are known to at least the hundredths place, we keep two decimal places in the sum, resulting in 142.49.
Step-by-step explanation:
To find the sum of 60.09 and 82.4, we add the two numbers together. When adding decimal numbers, the decimal point must be aligned. Here's how it is done step-by-step:
60.09
+ 82.4
We write 82.4 as 82.40 so that both numbers have the same number of decimal places. Now we add:
60.09
+ 82.40
------
142.49
We place the decimal point directly below the other decimal points in the sum. However, when dealing with significant figures, we notice that the number 82.4 has only one digit after the decimal. However, to report our answer, we look at the original numbers, which are accurately known to the hundredths place for the number 60.09. Therefore, we do not need to drop any numbers or round and the final sum is 142.49.