how to round whole numbers

How to Round Whole Numbers

A Number LineWhen rounding number, some times it helps to

remember and to use a number line.

| | | | | | | | | | | 0 10 20 30 40 50 60 70 80 90 100

| | | | | | | | | | 100 200 300 400 500 600 700 800 900 1000

| | | 1 000 000 2 000 000 3 000 000

BASIC RULES1. If the number to the RIGHT of the Rounding Number is 5 or

more (5, 6, 7 8 or 9) then the LEFT (Rounding Number) number goes UP by ONE place.

2. If the number to the RIGHT of the Rounding Number is 4 or less (4, 3, 2, 1 or 0) then the LEFT (Rounding Number) number remains the SAME.

3. Every number AFTER the Rounding Number becomes 0.

4. Everything BEFORE the Rounding Number remains the same.

5. If the Rounding Number is a 9 and it goes up by one, then a 0 is placed in the Rounding Number Place and 1 is moved to the next place to the LEFT. (same as carrying in adding)

How to Round Whole Numbers to the Tens Place

Use a number line to help you visualize

Example: Round 78 to the nearest tens place

| | | | | | | | | | 70 8078

1. Underline the place you want to round to.

Here we want the tens place 78


2. Look to the right of the place you want to round to,

Now look to the right of the 78 tens place - If the digit is 5, 6, 7, 8 or 9 – the digit in the tens place

goes UP by 1 - If the digit is 0, 1, 2, 3 or 4 – the digit in the tens place

STAYS THE SAME

Look here

The 7 in the tens place 78 80 goes up by 1 to 8



3. Next, the digits to the right of the rounding place become zero.

Now the 8 becomes zero 78 becomes 80

4. Anything to the left of the rounding place remains the same.

So 78 rounded to the nearest tens place is 80



| | | | | | | | | | 120 130123

To Round: 123 Here is the tens placeLook to the right 3, so the 2 in the tens place stays the same.On the left On the left hand side, all stays the same

123 rounds to 120



Example: Round 1 099 to the nearest tens place

| | | | | | | | | |

To Round: 1099 Here is the tens place with 9 to its right The 9 in the tens place goes up by one. **But, 9 goes to 10 and we only have one place 1100 So we need to move over one more place to the left adding 1 to the hundreds place and 0 to the tens place. All on right changes to zero.

1 099 rounds to 1 100

1090 11001099


Example: Round the following to the nearest tens place

To Round: 265234 2 34345 67865 723199 7891 222 222

070230 2 34045 68065 720199 7901 222 220

__265234 2 34345 67865 723199 7891 222 222

Look to the value of the place to the right of the tens place

PRACTICERound the following numbers to the nearest tens place.

a) 45

b) 67

c) 123

d) 456

e) 890

f) 1232

b) 70

a) 50

c) 120

d) 460

e) 890

f) 1 230

How to Round Whole Numbers to the Hundreds Place


Example: Round 145 to the nearest hundreds place

| | | | | | | | | | 100 200145


Here we want the hundreds place 145



Now look to the right of the 145 tens place - If the digit is 5, 6, 7, 8 or 9 – the digit in the hundreds

place goes UP by 1 - If the digit is 0, 1, 2, 3 or 4 – the digit in the hundreds

place STAYS THE SAME

The 1 in the hundreds place 145 100 stays the same



Now the 4 and 5 becomes zero 145 becomes 100


So 145 rounded to the nearest hundreds place is 100




Example: Round the following to the nearest hundreds place

To Round: 265234 2 34345 67865 723199 7891 222 222

0100200 2 30045 70065 700199 8001 222 200

_ _ 2_65234 2 34345 67865 723199 7891 222 222

Look to the value of the place to the right of the hundreds place

PRACTICERound the following numbers to the nearest hundreds place.

a) 49

b) 136

c) 293

d) 456

e) 1 890

f) 12 345

b) 100

a) 0

c) 300

d) 500

e) 1 900

f) 12 300

How to Round Whole Numbers to the Thousands Place


Example: Round 9 871 to the nearest thousands place

| | | | | | | | | | | 9000 10 0009 871


Here we want the thousands 9 871


Now look to the right of the 9 871 thousands place - If the digit is 5, 6, 7, 8 or 9 – the digit in the thousands

place goes UP by 1 - If the digit is 0, 1, 2, 3 or 4 – the digit in the thousands


The 9 in the thousands place 9 871 10 000 goes up by 1




Now the 8,7 and 1 becomes zero 9 871 becomes 10 000


So 9 871 rounded to the nearest thousand place is 10 000




Example: Round the following to the nearest thousands place

To Round: 265234 2 34345 67865 723199 7891 222 222

000 2 00046 00066 000200 0001 222 000

_ _ _ 2_ _65_234 2 34345 67865 723199 7891 222 222

Look to the value of the place to the right of the thousands place

PRACTICERound the following numbers to the nearest thousands place.

a) 1 234

b) 78 902

c) 12 666

d) 9 987

e) 2 890

f) 1 234 512

b) 79 000

a) 1 000

c) 13 000

d) 10 000

e) 3 000

f) 1 235 000


Example: Round 19 012 to the nearest ten thousands place

| | | | | | | | | | 19 000 20 000

19 012


Here we want the ten thousands place 19 012

How to Round Whole Numbers to the Ten Thousands Place


Now look to the right of the 19 012 ten thousands place - If the digit is 5, 6, 7, 8 or 9 – the digit in the ten

thousands place goes UP by 1 - If the digit is 0, 1, 2, 3 or 4 – the digit in the ten

thousands place STAYS THE SAME

The 1 in the ten thousands place 19 012 20 000goes up by one




All the numbers on the 19 012 becomes 20 000right becomes zero4. Anything to the left of the rounding place remains the same.

So 19 012 rounded to the nearest ten thousands place is 20 000




Example: Round the following to the nearest ten thousands place

To Round: 265234 2 34345 67865 723199 7891 222 222

070230 2 34045 68065 720199 7901 222 220

_ _ 2_65234 2 34345 67865 723199 7891 222 222


PRACTICERound the following numbers to the nearest ten thousands

place.

a) 45 653

b) 567 809

c) 12 342 565

d) 456 789

e) 112 343

b) 570 000

a) 50 000

c) 12 340 000

d) 460 000

e) 110 000



| | | | | | | | | | 100 200145



How to Round Whole Numbers to the Hundred Thousands Place


Example: Round the following to the nearest hundred thousands place

To Round: 265234 2 34345 67865 723199 7891 222 222

070230 2 34045 68065 720199 7901 222 220

_ _ 2_65234 2 34345 67865 723199 7891 222 222


PRACTICERound the following numbers to the nearest hundred

thousands place.

a) 455 555

b) 156 789

c) 12 345 876

d) 12 000 542

e) 334 334

b) 200 000

a) 500 000

c) 12 300 000

d) 12 000 000

e) 300 000



| | | | | | | | | | 100 200145



How to Round Whole Numbers to the Millions Place


Example: Round the following to the nearest millions place

To Round: 265234 2 34345 67865 723199 7891 222 222

070230 2 34045 68065 720199 7901 222 220

_ _ 2_65234 2 34345 67865 723199 7891 222 222


PRACTICERound the following numbers to the nearest millions place.

a) 1 455 555

b) 34 156 789

c) 999 999

d) 13 567 789

e) 27 800 000

b) 34 000 000

a) 1 000 000

c) 1 000 000

d) 14 000 000

e) 28 000 000

Some Examples:

1. Round to the nearest 10

12 ____________

Or use a number line is 12 closer to 10 or to 20?

Examples Because ...

3.1416 rounded to hundredths is 3.14 ... the next digit (1) is less than 5

1.2635 rounded to tenths is 1.3 ... the next digit (6) is 5 or more

1.2635 rounded to 3 decimal places is 1.264 ... the next digit (5) is 5 or more

134.9 rounded to tens is 130 ... the next digit (4) is less than 5

12,690 rounded to thousands is 13,000 ... the next digit (6) is 5 or more

1.239 rounded to units is 1 ... the next digit (2) is less than 5

how to round whole numbers

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