Rounding Whole Numbers

• http://www.youtube.com/watch?v=CaP61n1r1TI

Remember

• Find your number • Look right next door• 4 or less just ignore• 5 or more, add 1 more• Everything after is a

zero, no more

• What is rounding? Rounding means changing a given number to the nearest ten, hundred, thousand, and so on.

• Numbers can be rounded to the nearest ten, the nearest hundred, the nearest thousand, and so on.

To round a number to a given place: • Step 1: Find your number

Find the place you are rounding to: ten, hundred, thousand or another place value and circle it.

ie: Round 6,438 to the nearest hundred

H th T th Th H T O

6 4 3 8

• Step 2: Look right next door (Look at the digit to its right) and underline it.

H th T th Th H T O

6 4 3 8

4 or less just ignore If the number you are rounding is followed by 0, 1, 2, 3, or 4, round the number down. (don´t change the number in the circle)ie: Look in the ten place of the number 6,438. We see a 3, so we don´t change circled number.

Everything after is a zero, no more

• Therefore: Round 6,438 to the nearest hundred = 6,400

H th T th Th H T O

6 4 3 8

H th T th Th H T O

6 4 0 0

Check this example now

To round a number to a given place: • Step 1: Find your number

Find the place you are rounding to: ten, hundred, thousand or another place value and circle it.

ie: Round 6,458 to the nearest hundred

H th T th Th H T O

6 4 5 8

• Step 2: Look right next door • (Look at the digit to its right) and underline it.

H th T th Th H T O

6 4 5 8

• 5 or more, add 1 more• If the number you are rounding is followed by 5,

6, 7, 8, or 9, round the number up. (add 1 to the number in the circle)

ie: Look in the ten place of the number 6,458. We see a 5, so we must add 1 to the number in the circle.

H th T th Th H T O

6 4 5 8

4+1 = 5

H th T th Th H T O

6 5

Everything after is a zero, no more

• Therefore: Round 6,438 to the nearest hundred = 6,500

H th T th Th H T O

6 5 0 0

Round 13,528 to the nearest ten.13,528 8 > 5

Round up 13,530 to 13,530

Round 13,528 to the nearest hundred13,528 2 < 5

Round down13,500 to 13,500.

Round 13,528 to the nearest thousand.13,528 5=5

Round up14,000 to 14,000

All the numbers to the right of the place you arerounding to become zeros.

Let´s sing and play

• https://www.youtube.com/watch?v=3hANJu4LlQU

• https://www.youtube.com/watch?v=3afU6JQG15I

• http://mrcrammond.com/games/2ring-centrev4.swf

• http://www.wartgames.com/themes/math/rounding.html

Using a number line to round a whole number to a given place.

• https://www.youtube.com/watch?v=UP7YmXJc7Ik

• You can use a number line to round a whole number to a given place.

2,683

Round 2,683 to the nearest hundred.

First, find the rounding place.

2683

Hundreds

Then, find the number on a number line.

2,683 is between 2600 and 2,700

• Round the number to the closest hundred on the number line.

2,700 is the closest hundred. Round 2,683 up to 2,700.

• Hint: If a number is located directly in the middle of the number line, round up.

Consider the number 4,827.– 4,827 rounded to the nearest ten is 4,830 – 4,827 rounded to the nearest hundred is

4,800 – 4,827 rounded to the nearest thousand is

5,000

Here are some more examples:– 34 rounded to the nearest ten is 30 – 6,809 rounded to the nearest hundred is

6,800 – 1,951 rounded to the nearest thousand

is 2,000

Why would you want to round a number?

Rounding is a form of estimation that you use when an approximation is good enough.

For example when you are buying a TV at the store. The costmight be marked at $279.00. You could say it is about $300.00.

Rounding is also good to use so that you know what to expect

for an answer. It is good to use this skill when you are plugging

numbers into a calculator. Ex. Let's say you are adding up your expenses for the month.Power: $230, Telephone: $79.68 Rent: $470 Car Payment:$822. To get a good approximation of the money you will needyou could round to the closest hundred:

• Power: $230 would be$200 Phone $79.68 would be $100Rent: $470 would be $500Car: $822 would be $800

Total: $1601 which is close to the estimated total of $1600

Let´s practice

• http://www.ixl.com/math/grade-4/rounding • http://www.brainingcamp.com/legacy/conten

t/concepts/rounding/

1. Round to the nearest thousand:a) 14,389 14,000 d) 9,520 _________ b) 219,610 _________ e) 756,239 _________ c) 365,492 ________ f) 189,743 _________

2. Round to the nearest ten thousand: a) 924,987 _________ d) 824,033 _________ b) 537,096 _________ e) 295,474 _________ c) 145,302 _________ f) 777,330 _________

3. Round to the nearest hundred thousands: a) 898,456 _________ d) 514,358 _________ b) 286,673 _________ e) 979,842 _________ c) 265.512 _________ f) 275,321 _________

3. Round to the nearest hundred: a) 847 _________ d) 333 _________ b) 2 978 _________ e) 5 496 _________ c) 5 048 _________ f) 555 _________

6. Round to the nearest hundred thousand: a) 929 689 _________ d) 754 300 _________ b) 103 232 _________ e) 222 678 _________ c) 965 123 _________ f) 449 987 _________