In a previous lesson, students reasoned about the multiple of 100 nearest to a given number. In this lesson, students extend this work to include multiples of 10. The work here prepares students to round numbers to the nearest ten and the nearest hundred in upcoming lessons.

Number lines are still a central representation early in the lesson. Later in the lesson, students begin to reason numerically and think about how they could find the nearest multiple of 10, or multiple of 100, if a number line is not provided. Students should be encouraged to consider alternative strategies and use what they know about place value, but can still draw a number line if it is needed. In the Lesson Synthesis, students learn that rounding is a formal way to say which number is closer to a given number, and that number is often a multiple of 10 or a multiple of 100.

In this lesson students are encouraged to begin reasoning numerically about finding the nearest multiple of 10 or 100. What evidence did you see of such reasoning?