# Rounding to the Nearest HundredFree 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.

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

b. During the work week from 5/7 till 5/11

 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

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This rounding lesson is taken from my book Math Mammoth Place Value 3.

#### 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.