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Rounding to the Nearest Hundred
Free lesson from HomeschoolMath.net

When we round to the nearest hundred, the numbers “residing” in the red areas (up to 850) on the number line are rounded to 800. The numbers in the blue areas are rounded to 900.

Again, distance matters. Numbers from 801 to 849 are closer to 800 than to 900.
Numbers from 851 to 899 are closer to 900 than to 800. And the “middle guy,” 850, is rounded up to 900:   850 ≈ 900.

1. Mark the numbers as dots on the number line (approximately) and round them
   to either 800 or 900.

a.

804 ≈ ________

859 ≈ _________

b.

825 ≈ ________

850 ≈ ________

c.

860 ≈ ________

847 ≈ ________

d.

808 ≈ ________

892 ≈ ________

 

When rounding to the nearest hundred, look at the TENS DIGIT of the number.

  • If that digit is 0, 1, 2, 3, or 4, you will round down to the previous hundred.
  • If that digit is 5, 6, 7, 8, or 9, you will round up to the next hundred.
728 ≈ ?   The tens digit
is 2, so round down:

728 ≈ 700

471 ≈ ?   The tens digit
is 7, so round up:

471 ≈ 500

956 ≈ ?   The tens digit
is 5, so round up:

956 ≈ 1000

2. Round these numbers to the nearest hundred.

a.

416 ≈ ________

837 ≈ _________

b.

529 ≈ ________

960 ≈ ________

c.

670 ≈ ________

557 ≈ ________

d.

254 ≈ ________

147 ≈ ________



Things work similarly on this number line when rounding to the nearest hundred:

  • Numbers up to 2,450 (the middle number) are rounded down to 2,400.
  • Numbers after 2,450 are rounded up to 2,500.
  • And the “middle guy,” 2,450, is rounded up.

3. Round these numbers to 2,400 or to 2,500. You can use the number line above to help you.

a.

2,412 ≈ _______

b.

2,429 ≈ _______

c.

2,478 ≈ ________

d.

2,490 ≈ ________

 

Rounding rules

When rounding to the nearest hundred, look at the TENS DIGIT of the number.

If the tens digit is 0, 1, 2, 3, or 4, you will
round down
to the previous hundred.

728 ≈ ?  The tens digit is 2, so round down:

728 ≈ 700

Notice: the hundreds digit does not
change
.

If that digit is 5, 6, 7, 8, or 9, you will
round up to the next hundred.

471 ≈ ?   The tens digit is 7, so round up:

471 ≈ 500

Notice: the hundreds digit increases by
one
, from 4 to 5.

Whether you round up or down, the tens and ones digits change to zeros.

4. Round these numbers to the nearest hundred.

a.  6,216 ≈ _________

b.  5,923 ≈ _________

c.  1,670 ≈ _________

d.  8,254 ≈ _________

e.  8,019 ≈ _________

f.  2,157 ≈ _________

g.  1,772 ≈ _________

h.  6,849 ≈ _________

i.  801 ≈ _________

j.  255 ≈ _________

k.  9,562 ≈ _________

l.  3,501 ≈ _________



Note especially!    4,952 ≈ ?

Now the tens digit is 5, so we round up. The hundreds digit (9) increases by one
(to ten hundreds). But we can't change 9 to 10 or we would get 41052!

Instead, those ten hundreds make a new thousand, so the thousands digit is incremented
by one. It is as if '49' changes to '50'.   So, we get  4,952 ≈ 5,000

5. Round these numbers to the nearest hundred.

a.  6,986 ≈ _________

b.  5,973 ≈ _________

c.  1,981 ≈ _________

d.  4,945 ≈ _________

e.  2,932 ≈ _________

f.  9,969 ≈ _________

g.    966 ≈ _________

h.  9,982 ≈ _________

i.    798 ≈ _________

 

6. Round these numbers to the nearest hundred.
    Place each answer in the cross-number puzzle.
 
a. e.        
           
b.          
          h.
f.   g.      
    c.      
           
  d.        
    Across:

    a. 2,264 ≈ _______

    b. 4,973 ≈ _______

    c. 4,248 ≈ _______

    d.  545 ≈ _______

Down:

e. 3,709 ≈ _______

f. 672 ≈ _______

g. 5,370 ≈ _______

h. 8,816 ≈ _______

 

7. Fill in, using rounded numbers.

   a. Usually, Mary receives about
       __________ spam emails daily, but on
       5/9 she got about ___________ spams.

    b. During the work week from 5/7 till 5/11
        she received about __________ spams.

Spam Emails Mary Received

Date Spams round to nearest 100
Mo 5/7 125  
Tu 5/8 97  
Wd 5/9 316  
Th 5/10 118  
Fr 5/11 106  



The ideas in this place value lesson are taken from the Place Value 3 book that I sell at MathMammoth.com. Only a few examples of each problem type are shown; you should make more problems of each kind for the student.

Math Mammoth Place Value 3

A self-teaching worktext for 3rd grade that covers four-digit place value, mental addition & subtraction with four-digit numbers, comparing, rounding, and estimating.

Download ($2.75). Also available as a printed copy.

=> Learn more and see the free samples!

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