Time Calculations with a Calculator


      Subscribe in NewsGator Online   Subscribe in Bloglines

Adding and subtracting time is often a complicated task. Addition isn't impossible, because the minutes and seconds can be added in their places, and then the seconds that exceed 59 can be reduced and converted to minutes. Subtraction can be much more tedious.

A simpler method is to apply the 940 rule. Here's how it works.

Take the time amounts and replace the colon separating the hours and minutes and replace it with a zero. For example, one minute and thirty seconds (1:30) becomes 1030. Add the various times in this converted format. When the final sum is determined, add 940 to it, then reconvert the zeroes back to colons to reveal the result.

Here's an example. Add 1:24, 2:12, 5:50 and 6:03.

+1:24
2:12
5:50
6:03

This becomes

+1024
2012
5050
6003

=14089

Add 940 to the result

+14089
940

=15029

Replace the zero with a colon and the result is 15:29.

Subtraction works the same way. Subtract 2:50 from 6:03.

-6003
2050

=3935
-940

=3013

Replace the zero with a colon to get 3:13.

Exception

Adding several times that are close to a full minute will not work properly with this approach. For example, 1:59 + 1:59 + 1:59. (Try it and you'll see the problem.) If you find an odd result with more than two addends, add the amounts separately. In this case, add 1059 + 1059 = 2118 + 940 = 3058. Then add 3058 + 1059 = 4117 + 940 = 5057.

If you don't want to keep splitting your addends, you can also use the commutative property of addition. If you add multiple times plus a single 940 and get a result that does not include a zero to convert to a colon, keep adding 940 until the result provides a number that can be converted back to a time. For example: 1059 + 1059 + 1059 + 1050 + 940 + 940 + 940 = 7047.



Commenting terms of use blog comments powered by Disqus

Webinars

Critical Aspects of Tower Site Safety

Learn the steps you can take to ensure a safe working environment at a tower site.

33 1/3 Things You Forgot

Think wire is just wire? Think again.

Podcast Archives

Radio Currents Podcast, Nov 24

FCC Commissioner Jonathan Adelstein seeks a PPM investigation, Nielsen steps into radio ratings with Cumulus, The NABEF seeks entires for the Celebration of Service to America Awards, Nautel opens a parts depot in Memphis, and Volvo makes HD Radio standard on nearly all models in 2009.

Radio Currents Podcast, Nov 17

Changes are expected in Washington when Obama takes office, Emmis Interactive signs several stations to its interactive platform and sales consulting services, MySimBook hires hired Doug Raines as vice president business development, and captioned HD Radio passes its test on election night.

Forum

The Radio magazine Forum

Pose a question, discuss an idea. This is your forum.

Blog

Talkback: The Radio Blog

Talkback, the Radio magazine blog, is your chance to post and comment on technical issues in radio.

Projects in Progress

Projects in Progress tracks facility installation projects from start to finish. Follow the progress of the WUVT-FM transmitter site upgrade.

Today in Radio History

Milestones From Radio's Past

The history of radio broadcasting extends beyond the work of a few famous inventors.

magazine cover image

Current Issue

Data Lifesaver

Without a doubt, we rely on data in virtually every facet of business and even in our personal lives.

Browse Back Issues