Rounding Whole Numbers

What is rounding? Rounding means changing a given number to the nearest ten, hundred, thousand, and so on. When rounding a number, you first need to ask: what are you rounding it to? 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 the place you are rounding to: ten, hundred, thousand or another place value. ie: Round 6,458 to the nearest hundred - In this case we are rounding to the hundred's place. Step 2: Decide what two multiples the number you are rounding is between. ie: We are rounding to the hundred's place so we would choose multiples of 100. So: 6,458 is between 6,400 and 6,500

Step 3 Look at the digit to its right. If the number you are rounding is followed by 5, 6, 7, 8, or 9, round the number up to the higher multiple. If the number you are rounding is followed by 0, 1, 2, 3, or 4, round the number down. ie: Look in the ten place of the number 6,458. We see a 5, so we must round to the higher number. Therefore: Round 6,458 to the nearest hundred = 6,500 On a number line, you can see how rounding a number approximates its value.

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.

All the numbers to the right of the place you are Round 13,528 to the nearest ten. 13,528 8 > 5 Round up 13,530 to 13,530 Round 13,528 to the nearest hundred 13,528 2 < 5 Round down 13,500 to 13,500. Round 13,528 to the nearest thousand. 13,528 5=5 14,000 to 14,000 All the numbers to the right of the place you are rounding to become zeros.

Here are some more examples: 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 cost might 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 need you could round to the closest hundred: Power: $230 would be$200 Phone $79.68 would be $100 Rent: $470 would be $500 Car: $822 would be $800 Total: $1601 which is close to the estimated total of $1600

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Activity

1. Round to the nearest thousand: a) 14 389 ________ d) 9,520 _________ b) 29 610 ________ e) 56,239 _________ c) 3 492 ________ f) 89 743 _________ 2. Round to the nearest ten thousand: a) 24 987 _________ d) 24 033 _________ b) 37 096 _________ e) 295 474 _________ c) 145 302 _________ f) 77 330 _________ 3. Round to the nearest ten: a) 89 _________ d) 514 _________ b) 2 673 _________ e) 97 _________ c) 265 _________ f) 2 753 _________

4. Round to the nearest hundred: a) 847 _________ d) 333 _________ b) 2 978 _________ e) 5 496 _________ c) 5 048 _________ f) 555 _________ 5. Round to the nearest hundred thousand: a) 929 689 _________ d) 754 300 _________ b) 103 232 _________ e) 222 678 _________ c) 965 123 _________ f) 449 987 _________