## Sig Figs When Adding and Subtracting

AmyL_3L
Posts: 50
Joined: Fri Aug 09, 2019 12:17 am

### Sig Figs When Adding and Subtracting

What rule do you use when you are adding or subtracting sig figs?

JamieVu_2C
Posts: 108
Joined: Thu Jul 25, 2019 12:16 am

### Re: Sig Figs When Adding and Subtracting

When adding or subtracting, you keep the significant figures for the least amount of places after the decimal point. For example, 150.0 + 0.507 would be 150.5. This is because 150.0 has one place after the decimal point, while 0.507 has 3. So, you keep the least number of places after the decimal in your final answer. The least number of decimal places is 1, so the answer would be 150.5 instead of 150.507.

Katherine Wu 1H
Posts: 104
Joined: Fri Aug 30, 2019 12:15 am
Been upvoted: 2 times

### Re: Sig Figs When Adding and Subtracting

For example, let's say these three numbers: 34.07 g, 70 g, and 60.0 g create the number 7070.3 g
34.07 g has 4 sig figs
70 g has 1 sig fig
60.0 g has 3 sig figs
7070.3 g would be rounded down to 7000 g because you always want to choose the number that has the least amount of sig figs. In this case, 1 sig fig because of 70 g.

emwoodc
Posts: 45
Joined: Fri Aug 09, 2019 12:16 am

### Re: Sig Figs When Adding and Subtracting

when adding or subtracting you use the number with the least sig figs and match the answer to it