A Significant Win
You may recognize this famous gold medalist. He’s Michael Phelps, the worldchampion swimmer. The times of worldclass athletes like Michael Phelps may be measured to the hundredths of a second. That’s important because the times are often very close. A new world record may be set by just a splitsecond difference in time.
Why It Matters
 The need for accuracy in timing athletic events makes significant figures important. Significant figures are the correct number of digits for reporting a measurement or calculation. Just the thought of significant figures may make you cringe, but using them really isn’t difficult. You just need to apply a few simple rules.

 How accurately must swimming times be measured, and how many significant figures are required? To answer this question, watch the video below. It shows Michael Phelps setting a new world record in an exciting 100meter race. Notice how little time separates his time in this race from the previous world record.
http://www.youtube.com/watch?v=2vK8iJgISXY
Can You Apply It?
Learn more about significant figures at the links below. Then answer the questions that follow.
 http://www.ducksters.com/kidsmath/significant_digits_or_figures.php
 http://web.campbell.edu/faculty/fetterman/Significant%20Figures.htm
 True or false: The number of significant figures is the minimum number of figures required to report a value without loss of accuracy.
 Which figures are significant?
 all nonzero figures
 any zeros between significant figures
 trailing zeros to the right of a decimal point
 all of the above
 Which figures are not significant?
 trailing zeros to the left of a decimal point
 leading zeros to the right of a decimal point
 leading zeros to the left of a decimal point
 two of the above
 How many significant figures are there in each of the following numbers?
 1000
 1000.0
 10.005
 0.005
 Why is it important to use significant figures when recording a measurement, such as an athlete’s time in a race?
 When using a digital measuring device, how many figures are significant?
 When using an analog (nondigital) measuring device, how many figures are significant?
 What significant figures would you record for the measurement of liquid in the graduated cylinder shown below? Why? (Assume that the cylinder is marked in milliliters.)
 In the swimming competition in the video above, what was Michael Phelps’ time? What was the previous world record? How much time did he shave off the previous world record?
 In this swimming competition, swimmer’s times were measured digitally. How many significant figures are there in Michael Phelps’ winning time? Why?