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Decimals

Decimals. Mr. Walker. What is a Decimal?. It is a dot after a number. Every whole number has a decimal on the end, even if it is not shown. A decimal means that the digits after it are less than one whole. Just part of something bigger.

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Decimals

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  1. Decimals Mr. Walker

  2. What is a Decimal? . • It is a dot after a number. • Every whole number has a decimal on the end, even if it is not shown. • A decimal means that the digits after it are less than one whole. Just part of something bigger. • A dollar is a whole. Fifty cents is just part of a dollar. . . . 25 356 122 . Means there are 25 and a little more, but not quite 26 25 75 . . 1 50

  3. Place Value Reading a Number with a Decimal Always use ‘and’ for the decimal 652.94 6 5 2 9 4 Six hundred fifty-two and ninety-four hundredths

  4. Place Value Reading a Number with a Decimal 142.4 1 4 2 4 One hundred forty-two and four tenths

  5. Place Value Reading a Number with a Decimal 957.03 9 5 7 0 3 Nine hundred fifty-seven and three hundredths

  6. Comparing Decimals • Think Money!! • If it does not look like money, then make it look like money by adding a zero at the end. Add a zero to the number on the left to make it comparable, or to make it look like money > 84.5 0 84.05 >,<, or = Which one would you rather have in your bank account? Remember, the alligator always eats the bigger number.

  7. Comparing Decimals (Try it) >,<, or = Add a zero Add a zero > < 39.2 0 39.02 5.09 5.9 0 Answer Answer Add a zero Add a zero = < 52.3 0 52.30 12.20 13.2 0 Answer Answer

  8. Adding and Subtracting Decimals When adding or subtracting decimals, you only need to remember two things… • Line up the decimals • Put zeros in all the empty spaces 12.4 .35 + 5.01 12.40 00.35 +05.01 12.4 + .35 + 5.01 17.76 Don’t forget to bring down the decimal

  9. Adding & Subtracting Decimals (Try) 12.2 + 6.05 + .1 125.3 – 118.05 1.72 + .01 +.6 12.20 06.05 +00.10 125.30 -118.05 1.72 0.01 +0.60 7.25 18.35 2.33 Answer Answer Answer

  10. Multiplying Decimals Multiplying decimals is very easy • Ignore the decimals until you are done • Then count all the digits to the • right of both decimals. That number • is the amount of spaces from the right • (in your answer) you will put your decimal 1.29 x 6.5 129 x 65 645 +7740 8385 1 2 3 .

  11. Dividing Decimals Dividing decimals is very easy • Just ignore it at first and do the problem • Then put the decimal (in your answer) right above where it is in the problem. 3.8 7 27.9 4 6 1 9 1 8 1 4 1 4 0

  12. Decimals are Fractions (money) .25 is the same as ¼ (4 quarters make a whole dollar, but I only have one of them, which equals 25 cents.) .50 is the same as ½(4 quarters make a whole dollar, but I only have two of them, which equals 50 cents or half a dollar.) .75 is the same as ¾(4 quarters make a whole dollar, but I only have three of them, which equals 75 cents.) 15.75 is the same as 15 ¾ (Fifteen dollars and three quarters or 75 cents.)

  13. Decimals are Fractions (others) You can find the fraction of any decimal based on place value. .34 is the same as 34/100 (the .34 goes into the hundredths place) .6 is the same as 6/10 (.6 only goes to the tenths place) .05 is the same as 5/100 (.05 goes to the hundredths place) 3 6 0 4 5

  14. Try Finding the Fractions from the Decimals 3.06 2.4 .34 6 100 34 100 4 10 3 2 Answer Answer Answer The 2 is a whole number and will go to the left of the fraction. .34 goes into the hundreths spot, so the denominator is a hundred. 3 4

  15. Try Finding the Decimals from the Fractions 2 100 23 100 5 10 4 7 4.02 7.5 .23 Answer Answer Answer 23 is over a hundred. Put 23 into the chart so that the 3 is in the hundreths spot. You could also say that since 100 has 2 zeros, all you need to do is write 23 and move the decimal (at the end of every whole number) two spaces to the left. 2 3

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