Adding and Subtracting Whole Numbers and Decimals Topic 2 EnVision Math

Rounding Numbers

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!

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

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

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 ignore Five or more, add one more

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

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?

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

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

Mountain Math practice….

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 20,000 + 7,000 + 900 + 50 + 9 2 809.004 ** All of the questions 1b-1k refer to the original number on 1a Answer these questions together—whole group

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) 4.49371 1b) 4.0 1c) 4.5 1d) 4.49 1e) 4.494 1f) 4.4937 1g) hundred thousandths 1h) four and forty-nine thousand three hundred seventy-one hundred thousandths Answer these questions together—whole group

Answer these Questions – for a grade White Board Brown Board

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) 200,000 + 3,000 + 100 + 20 + 3 2) 2.90 1a) 18.732964 1b) 19.0 1c) 18.7 1d) 18.73 1e) 18.733 1f) 18.7330 1g) millionths 1h) eighteen and seven hundred thirty-two thousand nine hundred sixty-four millionths