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Lesson 1 — Activity 1: Rounding Whole Numbers
Completion requirements
Lesson 1 — Activity 1: Rounding Whole Numbers
Getting Ready
Think about what you already know about the place value of numbers. Remember that place value is the value of a number based on the place or position in that number.
Below are the place values of this number.
Try This:
Identify the place value of the underlined digit in the following numbers:

3,456
 775,525
 32,194

3,456: 5 is in the tens position

775,525: 7 is in the ten thousands
position
 32,194: 4 is in the ones position
You will consider place value as you complete this first activity.
Have you ever watched someone who has done a lot of cooking or baking make something? Do they always use a measuring spoon for something like adding salt to the ingredients?
You may have seen your mother or grandmother just pouring a bit out of the container and saying, “That's about a teaspoon of salt” and going on with the recipe. She was just estimating the amount of salt to use.
Sometimes working with numbers is similar. You don't have to be exact; you can estimate.Think of it this way: if there were 1,000,050 people at an outdoor concert, you could say there were about a million people there.
This is known as rounding a number.
Estimating, or being able to guess and come close to a correct answer, is an important part of mathematics and a very handy tool for everyday life. You should get in the habit of estimating amounts of money, lengths of time, distances, and many other physical quantities. Rounding is a kind of estimating.
Think about these examples of rounding:
Temperature:
Daily
temperatures are often rounded to the nearest degree Celsius. E.g.,
25.7°C is generally reported as 26°C.
Temperature:
Daily temperatures are often rounded to the nearest degree Celsius. E.g., 25.7°C is generally reported as 26°C.
 Money:People often use rounding and estimating at a store to make sure they have enough money to pay for items before they get to the cashier.

Using large
numbers:
Newspapers often round large numbers to take up less space.They may print $10M rather than $10,490,721.00. When adding or subtracting large numbers mentally, it is easier to round them first!
The following is the general process for rounding any number:

First, look at the number to the right of the place you wish to work with.

Second, if that number is 4 or less, round the number down.

Third, if that number is 5 or greater, round the number up.
Here's an example of the number 547 rounded to the nearest ten:

Find the place value to be rounded and highlight it in the digit:
547
(4 is in the tens place)
 Underline the digit to the right of the highlighted number:
547
(7 is to the right of 4)
547
(4 is in the tens place)547
(7 is to the right of 4) If the underlined digit is 4 or less, round down. If it is greater than 4, skip to the next step. (7 is greater than 4, so go to the next step.)

If the underlined digit is 5 or greater, round up. To round up, increase the highlighted number by one and change any digits to its right to zeros:
547
becomes550
Here are some further examples of rounding in everyday situations. Click on each box below.

Find the place value to be rounded and highlight it in the digit:
1,237
(2 is in the hundreds place)

Underline the digit to the right of the highlighted number:
1,237
(3 is to the right of 2)

If the underlined digit is 4 or less, round down. If it is greater than 4, skip to the next step. To round down, change the underlined digit and any other digits to its right to zeros.
1,237
(3 is 4 or less, so round down):
1,237
becomes
1,200

Glen spent approximately $1,200 for his new computer.
1,237
(2 is in the hundreds place)1,237
(3 is to the right of 2)1,237
(3 is 4 or less, so round down):1,237
becomes1,200
First car: $4,253:

Find the place value to be rounded and highlight in the digit: 4,353 (4 is in the thousands place)

Underline the digit to the right of the highlighted number:
4,253
(2 is to the right of 4)

If the underlined digit is 4 or less, round down. If it is greater than 4, skip to the next step. To round down, change the underlined digit and any other digits to its right to zeroes.
4,253
(The highlighted number is 4 or less, so round down)
4,253
becomes
4,000
when rounded to the nearest thousand.

The first car costs approximately $4,000.
4,253
(2 is to the right of 4)4,253
(The highlighted number is 4 or less, so round down)4,253
becomes4,000
when rounded to the nearest thousand.

Find the place value to be rounded and highlight it in the digit:
8,765
(8 is in the thousands place)

Underline the digit to the right of the highlighted number:
8,765
(7 is to the right of 8)
 If the highlighted digit is 4 or less, round down. If it is greater than 4, skip to the next step. (7 is greater than 4, so go to the next step.)

If the underlined digit is 5 or greater, round up. To round up, increase the highlighted number by one and change any digits to its right to zeroes.
8,765
becomes9,000
when rounded to the nearest thousand.

The second car costs approximately $9,000.