Exploring Values That Round to a Given Amount

Author:GeoGebra Content Team

Explore which whole numbers round to a given value using number lines. Connect rounding intervals to upper and lower bounds.

Task 1

Putting It All Together

Answer these open ended questions on your own or with others to form deeper math connections.

Task 2

Why is the endpoint of the interval not included as a possible value that rounded yields the given one?

Task 3

Another way to write the error interval (mostly used in physics, where measuring instruments are used) is by adding and subtracting the precision of the instrument. For example, if we measure a temperature of , and the thermometer’s precision is , we will write that the temperature is Write the error interval of this measurement, using the inequality notation.

Task 4

What are the lower and upper limits of the error interval for 122 miles, measured to the nearest 100 miles? Do you think that this degree of accuracy is a good choice to describe a length of 122 miles?

Task 5

Police stated that 62000 people (rounded to the nearest thousand) participated in an event. What is the least number of people that attended the event?