Adding Significant Figures (Sig Fig) Calculator


Adding Significant Figures

Enter Numbers to Add:


This Adding Significant Figures Calculator computes the addition of the numbers entered in and places the resultant value into proper significant figures.

Significant figures, or digits, are the values in a number that can be counted on to be accurate. Significant digits in a number are those values which can be known with certainty or a high degree of confidence, while insignificant digits are those which we do not trust as very accurate.

Significant digits are used extensively during measurements. Different measurement tools can record measurements of differing accuracy. Some measurement tools can record much more in detail than other measuring tools. For example, if we have a ruler that only measures centimeters, we can measure to one-hundredth of a meter. If we now change the ruler and get one which measures millimeters, we can measure to one-thousandth of a meter. Thus, we can have an extra significant digit, because the ruler is more detailed and allows for more accuracy of measurement.

It is important to be honest when making a measurement, so that the resulant value does not appear to be more accurate than the equipment used to make the measurement allows. And how we make the recorded value honest is by controlling the number of digits, or significant figures, used to report the measurement. The recorded value cannot have more significant digits than the measuring tool allows. This is why proper sig fig are important.

When adding significant digits, the amount of significant digits that will be in the final answer is determined by the number of significant digits present after the decimal place in the numbers we are adding. The final resultant value will have the same number of decimal place values as the addend with the least amount of decimal places. Thus, if we have the numbers 254.6 and 234.789 being added, the final resultant will have 1 decimal place, since one of the addends only contains one decimal place. If any of the addends have no decimal places, then the final addition resultant value will have no decimal places. If the addend with the lowest amount of decimal places is 1, the final resultant will hold 1 decimal place. If the addend with the lowest addend is 2, the final resultant will hold 2 decimal places, and so on.

This is the only rule to follow when adding numbers and keeping proper significant figures.

To use this calculator, a user simply enters in the addition problem into the text box, and clicks the 'Calculate' buton. The resultant value in proper significant figures will be automatically computed and displayed.

Being that electronics, like any other science, deals with measurements, knowing how to add significant figures may be important. Depending on the measuring tool in use determines how accurate it can measure. Using the proper number of significant figures may be extremely important.


What is 234.3 + 11.16?

234.3 + 11.16= 245.5

Being that one of the addends only has 1 decimal place, the final resultant value contains only one decimal place.

What is 131.256 + 718.12?

131.256 + 718.12= 849.38

Being that one of the addends has only 2 decimal places, the final resultant value contains 2 decimal places.

What is 131 + 23.2?

131 + 23.2= 154

Being that one of the addends has no decimal places, the final resultant value has no decimal places.

Related Resources

Subtracting Significant Figures Calculator

Multiplying Significant Figures Calculator

Dividing Significant Figures Calculator

Significant Figures (Sig Fig) Calculator

Significant Figures Rounding Calculator