• MA.5.NSO.1 Number Sense and Operations

Understand the place value of multi-digit numbers with decimals to the thousandths place.

MA.5.NSO.1.5

Round multi-digit numbers with decimals to the thousandths to the nearest hundredth, tenth or whole number. Example: The number 18.507 rounded to the nearest tenth is 18.5 and to the nearest hundredth is 18.51.

Purpose and Instructional Strategies
The purpose of this benchmark is for students to think about the magnitude of multi-digit numbers with decimals to round them to the nearest hundredth, tenth or whole number. In Grade 5, the expectations for rounding are to the nearest hundredth and to digits other than the leading digit, e.g., round 29.834 to the nearest hundredth. Students have experience rounding whole numbers to any place in Grade 4 (MA.4.NSO.1.4). Rounding skills continue to be important in later grades as students solve real-world problems with fractions and decimals (MA.6.NSO.2.3) and work with scientific notation (MA.8.NSO.1.4).

 Instruction should develop some efficient rules for rounding fluently by building from the basic strategy of - “Is 29.834 closer to 20 or 30?” Number lines are effective tools for this type of thinking and help students relate the placement of numbers to benchmarks for rounding. (MTR.3.1, MTR.5.1)

 The expectation is that students have a deep understanding of place value and number sense in order to develop and use an algorithm or procedure for rounding. Additionally, students should explain and reason about their answers when they round and have numerous experiences using a number line and a hundred chart as tools to support their work with rounding.

Common Misconceptions or Errors
 Students may confuse benchmarks by which numbers can round. For example, when rounding 29.834 to the nearest tenth, they may confuse that the benchmarks are 29.8 and 29.9. The reliance on mnemonics, songs or rhymes during instruction can often confuse students further because it may replace their motivation to think about the benchmark numbers.

Round 29.834 to the nearest whole number. Identify between which two whole numbers 29.834 lies on a number line.

Round 29.834 to the nearest tenth. Identify between which two tenths 29.834 lies on a number line.

Round 29.834 to the nearest hundredth. Identify between which two hundredths 29.834 lies on a number line.

Instructional Items
Instructional Item 1
Which of the following are true about the number 104.029?
a. 104.029 rounded to the nearest whole number is 4.
b. 104.029 rounded to the nearest whole number is 104.
c. 104.029 rounded to the nearest tenth is 104.2.
d. 104.029 rounded to the nearest hundredth is 104.02.
e. 104.029 rounded to the nearest hundredth is 104.03.

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