Grade 3
  1. Number Sense and Numeration  1.1. Understanding Numbers  1.1.1. Reading and Writing Numbers up to 10,000  1.1.2. Place Value up to Thousands  1.1.3. Comparing and Ordering Numbers  1.1.4. Rounding Numbers to the Nearest Ten and Hundred  1.1.5. Skip Counting by 2s, 5s, 10s, and 100s up to 1,000  1.2. Operations with Whole Numbers  1.2.1. Addition and Subtraction up to 1,000  1.2.2. Multiplication Facts (up to 10 x 10)  1.2.3. Division Facts (up to 100)  1.2.4. Multiplication as Repeated Addition  1.2.5. Division as Equal Sharing  1.2.6. Word Problems with Addition, Subtraction, Multiplication, and Division  1.3. Estimation  1.3.1. Estimating Sums and Differences  1.3.2. Estimating Products and Quotients  1.4. Understanding Even and Odd Numbers
  2. Fractions and Decimals  2.1. Understanding Fractions  2.1.1. Identifying and Representing Fractions  2.1.2. Fractions of a Whole and Part of a Set  2.1.3. Comparing and Ordering Fractions with Like Denominators  2.1.4. Equivalent Fractions  2.1.5. Simple Fraction Word Problems  2.2. Introduction to Decimals  2.2.1. Tenths and Hundredths as Decimals  2.2.2. Relationship between Fractions and Decimals
  3. Measurement  3.1. Length  3.1.1. Measuring in Centimeters and Meters  3.1.2. Comparing and Ordering Lengths  3.1.3. Estimating Lengths  3.1.4. Converting Between Centimeters and Meters  3.2. Mass  3.2.1. Measuring in Grams and Kilograms  3.2.2. Estimating and Comparing Mass  3.3. Capacity  3.3.1. Measuring in Milliliters and Liters  3.3.2. Estimating and Comparing Capacity  3.4. Time  3.4.1. Telling Time to the Nearest Minute  3.4.2. Calculating Elapsed Time  3.4.3. Using a Calendar  3.4.4. Understanding A.M. and P.M.  3.5. Area and Perimeter  3.5.1. Calculating Perimeter of Simple Shapes  3.5.2. Estimating and Measuring Area of Shapes  3.5.3. Finding Area by Counting Squares
  4. Geometry  4.1. Properties of Shapes  4.1.1. Identifying 2D Shapes (Triangles, Quadrilaterals, Circles, etc.)  4.1.2. Identifying 3D Shapes (Cubes, Spheres, Cylinders, etc.)  4.1.3. Describing Attributes of 2D and 3D Shapes  4.1.4. Recognizing Parallel and Perpendicular Lines  4.2. Symmetry and Transformations  4.2.1. Recognizing Lines of Symmetry  4.2.2. Identifying Flips, Slides, and Turns  4.3. Angles  4.3.1. Understanding Right Angles  4.3.2. Comparing Angles (Acute, Right, Obtuse)
  5. Data Management and Probability  5.1. Data Collection and Organization  5.1.1. Collecting Data using Surveys and Experiments  5.1.2. Organizing Data using Tally Charts and Tables  5.2.1. Creating and Interpreting Pictographs  5.2.2. Creating and Interpreting Bar Graphs  5.2.3. Reading Simple Line Graphs  5.3. Probability  5.3.1. Understanding Basic Probability Terms (Certain, Possible, Impossible)  5.3.2. Predicting Outcomes  5.3.3. Simple Probability Experiments
  6. Patterns and Algebra  6.1. Patterns  6.1.1. Identifying and Extending Numeric Patterns  6.1.2. Identifying and Extending Shape Patterns  6.1.3. Creating Patterns Using Rules  6.2. Introduction to Algebra  6.2.1. Understanding Variables as Unknowns  6.2.2. Solving Simple Addition and Subtraction Equations  6.2.3. Using Patterns to Solve Problems
  7. Problem-Solving Skills  7.1. Strategies for Problem-Solving  7.1.1. Using Pictures or Diagrams  7.1.2. Identifying Patterns in Problems  7.1.3. Making Organized Lists  7.1.4. Guessing and Checking  7.1.5. Using Logical Reasoning  7.1.6. Breaking Down Problems into Steps

Grade 3 → Number Sense and Numeration → Understanding Numbers ↓


Rounding Numbers to the Nearest Ten and Hundred


Understanding numbers and how to manipulate them is an essential part of learning math in grade 3. One of the skills you will learn is how to round numbers to the nearest ten and hundred. This skill helps you estimate numbers and makes it easier to work with them in calculations. Let’s take a deeper look into this topic and explore it in detail.

What is rounding?

Rounding is a method used to simplify numbers. When you round a number, you are finding the nearest value to a specific "place," such as the nearest ten or nearest hundred. The result is usually an easier number to use in quick mathematical estimations or mental calculations.

Why do we round numbers?

There are several reasons to round off numbers:

  • Making it easier to understand and work with numbers.
  • To make calculations easier when exact numbers are not needed.
  • Getting a quick estimate that is fairly close to the real number.

How to round numbers to the nearest tens

Rounding to the nearest ten is about finding what ten a number is closest to. Follow these steps to round numbers to the nearest ten:

  1. Look at the number in the units place (the rightmost digit of the number).
  2. If this number is less than 5, round it down. This means that you change the ones digit to 0 and leave the rest of the digits unchanged.
  3. If this number is 5 or greater, round it up. This means you add 1 to the tens digit and change the units digit to a 0.

Visual example

70 80 90 100

For example, if you have the number 78, look at the 8 in the ones place. Since 8 is greater than 5, you would round it up. So, 78 rounded to the nearest tens would be 80.

Text example

Let's round off another number 32. Look at the 2 in the ones place. Since 2 is less than 5, we round down, which means the tens digit stays the same, and the ones digit becomes 0. So, 32 rounded to the nearest tens is 30.

How to round numbers to the nearest hundred

Rounding to the nearest hundred covers a slightly larger range of numbers. The steps for rounding to the nearest hundred are as follows:

  1. Look at the number in the tens place (second digit from the right).
  2. If this number is less than 5, round it down. This means that the tens and ones digits become 0, and the rest of the digits remain unchanged.
  3. If this number is 5 or greater, round it up. This means you add 1 to the hundreds digit and the tens and units digits become 0.

Visual example

100 200 300 400 500

Consider the number 478. The digit in the tens place is 7. Since 7 is greater than 5, we round it up. Therefore, the number 478 rounded to the nearest hundred is 500.

Text example

Let's try rounding the number 326. Look at the 2 in the tens place. Since 2 is less than 5, we round down, which means the hundreds digit remains the same, and both the tens and units digits become 0. Therefore, 326 rounded to the nearest hundred is 300.

Practice rounding numbers

Practice makes perfect! Try rounding these numbers:

  • Round 67 to the nearest tenth.
  • 152 Round off to the nearest hundred.
  • 44 Round off to the nearest ten.
  • Round off 876 to the nearest hundred.

The answers are as follows:

  1. Round off 67 to 70 (nearest ten).
  2. Round off 152 to 200 (nearest hundred).
  3. Round off 44 to 40 (nearest ten).
  4. Round off 876 to 900 (nearest hundred).

Special cases in rounding

Sometimes when rounding, you may get numbers that are exactly in the middle of two tens or hundreds. In such cases, there is a convention of rounding down. For example, the number 50 is exactly in the middle of 40 and 60. We round it up to 60.

Similarly, 150 is between 100 and 200. Thus, it is rounded off to 200.

Conclusion

Rounding numbers plays an important role in simplifying math. It helps eliminate estimation which makes mental arithmetic easier and makes handling large numbers much easier. When you learn to round numbers to the nearest ten and hundred, you develop an essential skill that helps you in many areas of math and daily life.

With practice, you will become proficient at rounding numbers. Always remember the rules of rounding: look at the ones digit to round to the nearest ten and look at the tens digit to round to the nearest hundred. If the digit you are considering is 5 or greater, round it up. Otherwise, round down.

Enjoy the roundness, and keep practicing!


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Rounding Numbers to the Nearest Ten and Hundred

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