Question

What is the answer of: 320.70 − (3103.0/1.3) in sigfig terms?

Answer 1

`-2079`

Explanation:

You have to break this calculation into two parts.

First, focus on the division. When you divide two numbers, the result cannot have more significant figures than the number with the least significant figures.

In this case, you have

• `1.3 ->` two sig figs;
• `3103.0 ->` five sig figs;

This means that the result of the division will have two sig figs.

`3103.0/1.3 = 2386.923 = 2400`

Now focus on the subtraction. This time you need to look at sig figs after the decimal. The result of the subtraction must have the same number of sig figs after the decimal as the number with the least significant figures after the decimal.

The thing to look out for is the fact that `2400` has no decimal, which is the same as saying it has zero sig figs after the decimal.

This means that the result must also ahve zero sig figs after the decimal.

`color(white)(.)320. color(red)(70) ->` two sig figs after the decimal;
`2400 color(white)(.)" "->` zero sig figs after the decimal#

The result of the subtraction will be

`320.70 - 2400 = -2079.3`

Round it to no sig figs after the decimal to get

`320.70 - 2400 = -2079.3 = color(green)(-2079)`