A can contains 375 milliliters of
soda. How much is left after 308
milliliters is removed?
This exercise involves combining
two numbers and keeping track of the significant figures involved for our
answer. We’re told that we start with 375
milliliters of soda in a can. We then remove 308 of those
milliliters. And we want to know how much is
leftover. What we’re doing is combining two
numbers through subtraction, that each have three significant figures in them.
If we perform the subtraction
directly, we get a result of 67 milliliters. But the question is, since each of
the numbers we added together has three significant figures, does our answer need to
have three as well? In other words, would we report
67.0 milliliters as our result?
We can recall the rule that when
we’re adding or subtracting numbers, the way to keep track of significant figures,
is to round our answer to the least number of decimal places involved. The two numbers we’re working with,
both have zero decimal places. So, our final answer will as
well. The amount of soda leftover is 67