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