Divide into groups of two or three students. The analysis of last digits of data can sometimes reveal whether values are the results of actual measurements or whether they are reported estimates. Find the lengths of rivers in the world, then analyze the last digits to determine whether those lengths appear to be actual measurements or whether they appear to be reported estimates. Instead of lengths of rivers, you could use other variables, such as the following:

• Heights of mountains
• Heights of tallest buildings
• Lengths of bridges
• Heights of roller coasters