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# Rounding whole numbers

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• 1. C.E.T. Colegio Myrang 4th grade Math Mrs. Shiara ROUNDING WHOLE NUMBERS
• 2.  Rounding means reducing the digits in a number while trying to keep its value similar. The result is less accurate, but easier to use.  There are 3 ways we can round numbers:  Using a number line:  Using place value  Using mental math ROUNDING
• 3.  Using a number line can be an easy method to round numbers, but you need to be very careful and place the numbers correctly.  Example: I want to round the number 134,456 to the nearest hundred thousand. In order to do that I must first know where the hundred thousand digit is. In this case, because I already know place value, I know that the hundred thousand place is the 1. USING A NUMBER LINE 1 3 4 4 5 6 Hundred thousands Ten thousands Thousands Hundreds Tens Ones
• 4.  I make a number line and place my number 134,456 between 100,000 and 200,000 thousand.  I can see that my number is closer to 100,000 than to 200,000 so:  134,456 rounded to the nearest hundred thousand = 100,000 USING A NUMBER LINE 134,456
• 5.  Number lines can take a lot of time, especially if you need to do a lot of exercises. A sometimes quicker way is using place value.  Using this method, you need to follow a couple of steps. Before following them, though, you need to remember place value in order to know the digit you are going to be rounding.  In this case, we want to round 134,456 to the nearest hundred thousand, so we have to determine which digit is in the hundred thousands place. USING PLACE VALUE 1 3 4 4 5 6 Hundred thousands Ten thousands Thousands Hundreds Tens Ones
• 6.  Step One:  Look to the number of the right.  134,456 Since we are going to round the 1, we need to look at the number on the right of it, which is the 3.  Step Two:  If it’s a number between 0-4, the rounding number stays the same.  If it’s a number between 5-9, add 1 to the rounding number.  3 is between 0-4, therefore, the rounding number (1) stays the same.  Step Three:  Replace the remaining numbers to the right of the rounding number with zero.  100,000 USING PLACE VALUE
• 7.  This is perhaps the easiest way to round, but you must be very careful when employing this method.  We follow the first few steps of the other methods:  Determine which digit we need to round.  Look to the digit on the right.  We are rounding 134,456 to the nearest hundred thousand. We need to round the 1, and we look to the 3 for guidance.  If we use mental math, we know that the number 13 (we took the two digits and made them a number) is closer to 10 than it is to 20, therefore, the first two digits remain as 10, and we simply replace the other digits with zero.  134,456 to the nearest hundred thousand = 100,000. USING MENTAL MATH
• 8.  548,652 to the nearest TEN THOUSAND.  Number line:  Place Value:  Look to the right of the ten thousands place.  8 is between 5-9 so I add 1 to my rounding number (4+1 = 5).  Turn the remaining numbers to zero.  550,000  Mental Math:  Look to the right of the ten thousands place.  48 is closer to 50 than to 40, so I replace those two digits with 50.  Turn the remaining numbers to the right to zero.  550,00 MORE EXAMPLES 5 4 8 6 5 2 Hth Tth Th H T O 548,652
• 9.  Practice these exercises in your notebook, then look at the Answer Key to see if you got it right! You may use the method that is easiest for you.  (1) 69,587 to the nearest HUNDRED  (2) 709,051 to the nearest HUNDRED THOUSAND  (3) 1,405 to the nearest TEN  (4) 33,985 to the nearest THOUSAND  (5) 95,201 to the nearest TEN THOUSAND PRACTICE!
• 10.  These are the answers to the previous slide’s exercises.  (1) 69,600  (2) 700,000  (3) 1,410  (4) 34,000  (5) 100,000 ANSWER KEY
• 11. Lesson prepared by: Mrs. Shiara Agosto For: 4th grade class, C.E.T. Colegio Myrang, Carolina, Puerto Rico Common Core Standards: CC.4.NBT.3 Use place value understanding to round multi-digit whole numbers to any place. DISCLAIMER: You may distribute, copy, and/or alter the contents of this lesson for personal or classroom use, as long as you leave this slide intact and give credit where credit is due. Thank you. CREDITS