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Adding and Subtracting Whole Numbers and Decimals Topic 2 EnVision Math

Adding and Subtracting Whole Numbers and Decimals Topic 2 EnVision Math

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Page 1: Adding and Subtracting Whole Numbers and Decimals Topic 2 EnVision Math

Adding and Subtracting Whole Numbers and Decimals

Topic 2

EnVision Math

Page 2: Adding and Subtracting Whole Numbers and Decimals Topic 2 EnVision Math

Rounding Numbers

Page 3: Adding and Subtracting Whole Numbers and Decimals Topic 2 EnVision Math

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!

Page 4: Adding and Subtracting Whole Numbers and Decimals Topic 2 EnVision Math

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

Page 5: Adding and Subtracting Whole Numbers and Decimals Topic 2 EnVision Math

474 Rounded to the hundreds becomes 500

Round 474 to the closest 10’s

474

Just ignore = 470

Page 6: Adding and Subtracting Whole Numbers and Decimals Topic 2 EnVision Math

What about decimal numbers

The same rules (and poem) apply!

Round 4.167 to the closest hundredths

4.167 Find your number

Look right next door

4.17 or 4.170 Four or less, just ignoreFive or more, add one more

Page 7: Adding and Subtracting Whole Numbers and Decimals Topic 2 EnVision Math

Remember

If you are asked to round to the nearest tenth…….your answer

stops in the tenths place!

Example: Round 42.73 to the closest tenth would be 42.7

Page 8: Adding and Subtracting Whole Numbers and Decimals Topic 2 EnVision Math

Special Case!Rounding a 9

Round 2.197 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?

Page 9: Adding and Subtracting Whole Numbers and Decimals Topic 2 EnVision Math

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

Page 10: Adding and Subtracting Whole Numbers and Decimals Topic 2 EnVision Math

Try these

Round to tenthstenths:

4.56 4.6

5.32 5.3

0.98 1.0

Round to hundredthshundredths

18.784 18.78

9.456 9.46

9.997 10.00

Page 11: Adding and Subtracting Whole Numbers and Decimals Topic 2 EnVision Math
Page 12: Adding and Subtracting Whole Numbers and Decimals Topic 2 EnVision Math
Page 13: Adding and Subtracting Whole Numbers and Decimals Topic 2 EnVision Math

Mountain Mathpractice….

Page 14: Adding and Subtracting Whole Numbers and Decimals Topic 2 EnVision Math

This is called the “Brown Board”because it has brown paper as thebackground….

Brown Board Questions~~1a. Write the number1b . Is this number even or odd?1c. Round this # to the nearest ten1d. Round this # to the nearest hundred1e. Round this # to the nearest thousand1f. Round this # to the nearest ten thousand1g. What number is 100 less than this #1h. What number is 100 more than this #1i . What number is 1000 less than this number1j. What number is 1000 more than this number1k. Write this number in expanded form2. Write this number

Answer these questions together—whole group

1a 27,9591b odd1c 27,9601d 28,0001e 28,0001f 30,0001g 27,8591h 28,0591i 26,9591j 28,9591k 20,000 + 7,000 + 900 + 50 + 92 809.004

~Answers~

** All of the questions 1b-1krefer to the originalnumber on 1a

Page 15: Adding and Subtracting Whole Numbers and Decimals Topic 2 EnVision Math

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.

Answer these questions together—whole group

1a) 4.493711b) 4.01c) 4.51d) 4.491e) 4.4941f) 4.49371g) hundred thousandths1h) four and forty-nine thousand three hundred seventy-one hundred thousandths

Again, all of theseanswers refer to the number on 1a

Page 16: Adding and Subtracting Whole Numbers and Decimals Topic 2 EnVision Math

Answer these Questions –for a grade

Brown Board White Board

Page 17: Adding and Subtracting Whole Numbers and Decimals Topic 2 EnVision Math

Answers to Mtn. Math questions

1a) 203,1231b) odd1c) 203,1201d) 203,1001e) 203,0001f) 200,0001g) 203,0231h) 203,2231i) 202,1231j) 204,1231k) 200,000 + 3,000 + 100 +

20 + 32) 2.90

1a) 18.7329641b) 19.01c) 18.71d) 18.731e) 18.7331f) 18.73301g) millionths1h) eighteen and seven hundred

thirty-two thousand nine hundred sixty-four millionths

Brown BoardWhite Board