### Whole Numbers, One Sig Fig

Posted:

**Sun Oct 08, 2017 2:37 pm**Say you get a number like 52 as an answer, but the smallest amount of sig figs in the problem is 1 sig fig. How would you round? Would you put the answer as 50?

Created by Dr. Laurence Lavelle

https://lavelle.chem.ucla.edu/forum/

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=9&t=21988

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Posted: **Sun Oct 08, 2017 2:37 pm**

Say you get a number like 52 as an answer, but the smallest amount of sig figs in the problem is 1 sig fig. How would you round? Would you put the answer as 50?

Posted: **Sun Oct 08, 2017 2:44 pm**

The number 50 still has two sig figs, so instead you'd have to write the number 50 in scientific notation without the decimal point. So it would be written as 5 x 10^1.

Posted: **Sun Oct 08, 2017 2:48 pm**

Hold up, sorry, the number 50 only has two sig figs if a decimal is in place, so you'd be fine with rounding down to 50. All though I'm not sure if you'd encounter a situation where there would only be one sig fig required to be in the answer.

Posted: **Sun Oct 08, 2017 3:18 pm**

Yes, you round 52 to 50 if you only need one sig fig. Generally, rounding in Chemistry is how you round normally except for numbers ending in 5 (round to nearest even number in this case).

To review general sig fig rules:

-All NON-ZERO numbers ARE significant

-leading 0s are NEVER significant (i.e., 0.0075 and .025 is 2 sig figs.)

-trapped 0s (0s in the middle) are ALWAYS significant (i.e., 504, 0.0206 are both 3 sig figs.)

-tricky part is in the trailing 0s (at the end of a number): if there is any decimal ANYWHERE in the number, then the trailing 0s ARE significant. For example, 500., 0.0200, and .250 all have 3 sig figs because a decimal exists somewhere in the number. Note: 500 is 1 sig fig while 500. is 3 sig figs.

To review general sig fig rules:

-All NON-ZERO numbers ARE significant

-leading 0s are NEVER significant (i.e., 0.0075 and .025 is 2 sig figs.)

-trapped 0s (0s in the middle) are ALWAYS significant (i.e., 504, 0.0206 are both 3 sig figs.)

-tricky part is in the trailing 0s (at the end of a number): if there is any decimal ANYWHERE in the number, then the trailing 0s ARE significant. For example, 500., 0.0200, and .250 all have 3 sig figs because a decimal exists somewhere in the number. Note: 500 is 1 sig fig while 500. is 3 sig figs.