Scientific American presents Math Dude by Quick & Dirty Tips. Scientific American and Quick & Dirty Tips are both Macmillan companies. Throughout history, circles have symbolized many things: unity, ...

The ability to round a number to a number of decimal places or to a number of significant figures is essential if answers are to be written to the correct degree of accuracy asked for in a question.

STEP 1 - WRAP RIBBON: Take the ribbon and wrap it around a glass. Mark where the ribbon overlaps itself. Image caption, STEP 2 - CUT CIRCUMFERENCE: Cut the ribbon at the point where it overlaps. You ...