significant figures

Part of the Computing fundamentals glossary:

The term significant figures refers to the number of important single digits (0 through 9 inclusive) in the coefficient of an expression in scientific notation . The number of significant figures in an expression indicates the confidence or precision with which an engineer or scientist states a quantity.

The table shows several examples of numbers written in standard decimal notation (first column) and in scientific notation (second column). The third column shows the number of signficant figures in the corresponding expression in the second column.

Decimal expression Scientific notation Sig. figs.
1,222,000.00 1.222 x 10 6 4
1.22200000 x 10 6 9
0.00003450000 3.45 x 10 -5 3
3.450000 x 10 -5 7
-9,876,543,210 -9.87654 x 10 9 6
-9.876543210 x 10 9 10
-0.0000000100 -1 x 10 -8 1
-1.00 x 10 -8 3

Significant figures are arrived at by rounding off an expression after a calculation is executed. In any calculation, the number of significant figures in the solution must be equal to, or less than, the number of significant figures in the least precise expression or element. Consider the following product:

2.56 x 10 67 x -8.33 x 10 -54

To obtain the product of these two numbers, the coefficients are multiplied, and the powers of 10 are added. This produces the following result:

2.56 x (-8.33) x 10 67+(-54)
= 2.56 x (-8.33) x 10 67-54
= -21.3248 x 10 13

The proper form of common scientific notation requires that the absolute value of the coefficient be larger than 1 and less than 10. Thus, the coefficient in the above expression should be divided by 10 and the power of 10 increased by one, giving:

-2.13248 x 10 14

Because both multiplicands in the original product are specified to only three significant figures, a scientist or engineer will round off the final expression to three significant figures as well, yielding:

-2.13 x 10 14

as the product.

Also see order of magnitude and scientific notation .

This was last updated in September 2005
Posted by: Margaret Rouse

Related Terms


  • disruptive technology

    - A disruptive technology is one that displaces an established technology and shakes up the industry. Harvard Business School professor Clayton M. Christensen coined the term.  In his 1997 best-sell... (

  • application program interface (API)

    - An application program interface (API) is code that allows two software programs to communicate with each other. Typically, APIs are released for third-party development as part of a software devel... (

  • Microsoft Windows Control Panel

    - The Microsoft Windows Control Panel is a management tool for the Windows operating system (OS) that allows end users to change settings and manage tasks within the OS.  (


  • Computing fundamentals

    - Terms related to computer fundamentals, including computer hardware definitions and words and phrases about software, operating systems, peripherals and troubleshooting.

  • Internet applications

    - This glossary contains terms related to Internet applications, including definitions about Software as a Service (SaaS) delivery models and words and phrases about web sites, e-commerce ...

Ask a Question. Find an Answer.Powered by

Ask An IT Question

Get answers from your peers on your most technical challenges

Ask Question

Tech TalkComment



    Contribute to the conversation

    All fields are required. Comments will appear at the bottom of the article.