length and width
Assume you are finding the area of a rectangle with a length of 6.8 m and a width of 6.9 m. When you multiply the length by the width on your calculator, the answer you get is 46.92 m 2 . Is this the correct answer? No; the correct answer is 46.9 m 2 . The correct answer must be rounded down so there is just one digit to the right of the decimal point. Thats because the answer cannot have more digits to the right of the decimal point than any of the original measurements. Using extra digits implies a greater degree of precision than actually exists. The correct number of digits is called the number of significant figures . To learn more about significant figures and rounding, you can watch the videos at the URLs below.