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Guide to Rounding Numbers





1. Rounding Whole Numbers


When rounding whole numbers, you'll decide on a place value to which you want to round. The number in the place value to the right of the one you're rounding will determine if you round up or down.


Steps:

  • Identify the digit in the place value to which you're rounding.

  • Look at the digit to its immediate right (check next door).

  • If that digit is 5 or greater, add 1 to the digit you're rounding and change all digits to its right to zeros.

  • If that digit is less than 5, keep the digit you're rounding the same and change all digits to its right to zeros.


Example: Rounding to the nearest tens.

  • 57 becomes 60 (because 7 is greater than 5)

  • 43 becomes 40 (because 3 is less than 5)



2. Rounding Decimal Numbers


Rounding decimal numbers follows a similar principle, but you'll be working with places to the right of the decimal point.


Steps:

  • Identify the digit in the decimal place to which you're rounding.

  • Look at the digit to its immediate right.

  • If that digit is 5 or greater, add 1 to the digit you're rounding and remove all digits to its right.

  • If that digit is less than 5, keep the digit you're rounding the same and remove all digits to its right.


Example: Rounding to two decimal places.

  • 3.147 becomes 3.15 (because 7 is greater than 5)

  • 5.632 becomes 5.63 (because 2 is less than 5)



3. Tips and Tricks


  • Rounding to the Nearest Whole Number: If you're rounding a decimal to the nearest whole number, you'll look at the first digit after the decimal point. If it's 5 or greater, round up. If it's less than 5, round down. Example:

    • 4.7 becomes 5

    • 6.4 becomes 6


  • Zeros Matter: When rounding, it's important to remember that zeros can impact the final rounded number, especially when rounding to a specific place value. Example:

    • Rounding 500.25 to the nearest hundred becomes 500 (not 5).


  • Midway Numbers: When a number is exactly halfway between two rounded values, the convention is to round up. Example:

    • 3.5 rounded to the nearest whole number becomes 4.



Remember, rounding is a valuable skill, especially when you need to make quick estimates or simplify numbers for easier calculations. Practice regularly with different numbers and place values to become proficient!



Practice Quiz:

1 - When rounding the number 67 to the nearest tens, what is the result?

a) 60

b) 65

c) 70

d) 68


2 - Which digit determines if you round up or down?

a) The digit in the place value you're rounding to

b) The digit to the immediate left of the place value you're rounding to

c) The digit to the immediate right of the place value you're rounding to

d) The last digit in the number


3 - When rounding 4.89 to one decimal place, what is the result?

a) 4.8

b) 4.9

c) 5.0

d) 4.80


4 - If you're rounding a decimal number to the nearest whole number and the first digit after the decimal point is 5, what should you do?

a) Round down

b) Round up

c) Keep it the same

d) Remove the decimal point


5 - When rounding 0.47 to one decimal place, what is the result?

a) 0.4

b) 0.5

c) 0.47

d) 0


6 - Which of the following numbers rounded to the nearest hundred is 500?

a) 449.25

b) 500.25

c) 551.25

d) 595.25


7 - When rounding 3.5 to the nearest whole number, what is the result?

a) 3

b) 4

c) 3.5

d) 3.0


8 - If you're rounding the number 1234 to the nearest hundreds, which digit will you look at to decide if you should round up or down?

a) 1

b) 2

c) 3

d) 4


9 - When rounding 6.02 to the nearest whole number, what is the result?

a) 5

b) 6

c) 7

d) 6.0


10 - Which of the following is NOT a reason for rounding numbers?

a) Making quick estimates

b) Simplifying numbers for easier calculations

c) Finding the exact value of a number

d) Making numbers more understandable




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