1. Adding and Subtracting Whole Numbers and Decimals
Topic 2
EnVision Math

2. Rounding Numbers

3. The rounding poem Find your number Look right next door
4 or less, just ignore
5 or more add one more!
Write this poem
down in your
notes!

4. Rounding Whole Numbers
Round 474 to the closest hundred.
474
Find your number
Look right next door
Four or less, just ignore
Five or more, add one more

5. 474 Rounded to the hundreds becomes 500
Round 474 to the closest 10’s
474
Just ignore = 470

6. What about decimal numbers
The same rules (and poem) apply!
Round to the closest hundredths
4.167
Find your number
Look right next door
4.17 or 4.170
Four or less, just ignore
Five or more, add one more

7. Remember
If you are asked to round to the nearest tenth…….your answer stops in the tenths place!
Example: Round to the closest tenth would be 42.7

8. Special Case! Rounding a 9
Round to the hundredths place
Since there is a “9” in the hundredths place consider the tenth and hundredths together – 19 – do you leave it at 19 or move it to 20?

9. Round 4.95 to the closest tenth
Since there is a “9” in the tenth spot consider the ones and tenths together…… should you leave it at 49 or move it to 50?
4.95 rounded to the nearest tenth is 5.0

10. Try these 4.56 4.6 5.32 5.3 0.98 1.0 Round to hundredths
Round to tenths:
4.56
4.6
18.784
18.78
5.32
5.3
9.46
9.456
10.00
0.98
1.0
9.997

13. Mountain Math practice….

14. This is called the “Brown Board” because it has brown paper as the background….
~Answers~
Brown Board Questions~~
1a. Write the number
1b . Is this number even or odd?
1c. Round this # to the nearest ten
1d. Round this # to the nearest hundred
1e. Round this # to the nearest thousand
1f. Round this # to the nearest ten thousand
1g. What number is 100 less than this #
1h. What number is 100 more than this #
1i . What number is 1000 less than this number
1j. What number is 1000 more than this number
1k. Write this number in expanded form
2. Write this number
1a 27,959
1b odd
1c 27,960
1d 28,000
1e 28,000
1f 30,000
1g 27,859
1h 28,059
1i 26,959
1j 28,959
1k 20, ,
** All of the questions 1b-1k refer to the original number on 1a
Answer these questions together—whole group

15. And….this is called the “White Board” because….
You guessed it…it has a white background.
Mountain Math Questions ~~ White Board ~~
1a) Write this number.
1b) Round to the nearest whole number.
1c) Round to the nearest tenth.
1d) Round to the nearest hundredth.
1e) Round to the nearest thousandth.
1f) Round to the nearest ten thousandth.
1g) Name the place of the last digit.
1h) Write this number in word form.
Again, all of these
answers refer to
the number on 1a
1a)
1b) 4.0
1c) 4.5
1d) 4.49
1e)
1f)
1g) hundred thousandths
1h) four and forty-nine thousand
three hundred seventy-one
hundred thousandths
Answer these questions together—whole group

16. Answer these Questions – for a grade
White Board
Brown Board

17. Answers to Mtn. Math questions
Brown Board
White Board
1a) 203,123
1b) odd
1c) 203,120
1d) 203,100
1e) 203,000
1f) 200,000
1g) 203,023
1h) 203,223
1i) 202,123
1j) 204,123
1k) 200, ,
2) 2.90
1a)
1b) 19.0
1c) 18.7
1d)
1e)
1f)
1g) millionths
1h) eighteen and seven hundred thirty-two thousand nine hundred sixty-four millionths