RECORDED CLASSESMATH 202 DECIMALS Every number has a decimal point. But it is often left unwritten. It goes to the right of the ones position. values between two integers rational numbers Deci- means 10 divisions of ten. Tenths position to the decimals right the numerals value divided by ten 0.3 equals 3/10 Positions follow in smaller amounts. hundredths position thousandths position divide by 100 divide by 1000 0.34 equals 34/100 0.347 equals 347/1000 Each position allows smaller values |
INDEX MATH 202 1. Decimals 444 2. Decimal Addition 333 3. Subtracting Decimals 333 4. Multiplying Decimals 333 5. Dividing Decimals 1 333 Rounding numbers Round the decimal to the hundredths position. closest numeral in that position 0.347 round up to 0.35 0.342 round down to 0.34 more positions more accuracy |
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DECIMAL ADDITION Meaning Clusters
for the bus for
10.5 minutes. You ride on the bus for
1.25 minutes. You want to know how much time you
spent. Line up the numbers by their decimal points and
work right to left. 10. 5 minutes + 1. 25 minutes 5 is the only digit in
the hundredths position. 10. 5 minutes + 1. 25 minutes .
5 minutes Add 2 and 5 from
the tenths position. 2 + 5 = 7 10. 5 minutes + 1. 25
minutes . 75 minutes Add 0 + 1 from the ones position. 0 + 1 = 1 10. 5 minutes + 1. 25
minutes 1. 75 minutes 1 is the only
digit in the tens position. 10. 5 minutes + 1. 25
minutes 11. 75 minutes |
MEMORY
TRIGGERS TESTS ______wait__________________________ ___________________________________ ______ride__________________________
_____________________time__________ ___________________________________ Line
up_____________________________ ___________________________________ __________________digit_____________ ___________________________________ Add________________________________ ___________________________________ ______________minutes______________ ___________________________________ 10.5________________________________ ___________________________________ Speed Learning format by
Carl Peterson ©2005 |
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SUBTRACTING DECIMALS Meaning Clusters You want to go to an amusement park 50 kilometers away. You travel 34.27 kilometers. How many kilometers remain
in the trip? Subtract the number of kilometers traveled from
the total distance. 50 – 34.27 Expand the 50 with a
decimal point and zeros in
the tenths and hundredths position. 50.00 – 34.27 Subtract the
digits in the hundredths position. 0 – 7 = -7 Borrow a one from the 0 in the tenths
position turning it into a 9. -7 + 10 = 3 50.09 0 – 34.2 7 3 Subtract the
digits in the tenths position. 9 – 2 = 7 50.09 0 – 34.2 7 .7
3 |
Subtract the digits in
the ones position. 0
– 4 = -4 Borrow
a one from
the 5 in the tens position. -4
+ 10 = 6 5
– 1 = 4 54 0.09 0 – 3 4. 2
7 6. 7
3 Subtract
the digits in the tens position. 4
– 3 = 1 54 0.09 0 – 3 4. 2
7 1
6. 7 3 The
amusement park is 16.73 kilometers away. MEMORY
TRIGGERS TESTS Subtract____________________________ ___________________________________ Borrow_____________________________
___________________digits____________ ___________________________________ _____________________tenths_________ ___________________________________ Speed Learning format by
Carl Peterson ©2005 |
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MULTIPLYING DECIMALS Meaning Clusters A worm travels 1.24 meters per hour. If the worm crawls for .2 hours how far will it
travel? 1.24 × .2 Multiply the digit of the bottom factor by the digit in the hundredths position of
the top factor. 2 × 4 = 8 1.24 × .2 8 Repeat this process with the digits in the tenths position and ones position of
the top factor. 2 × 2 = 4 1.24 ×
.2_ 4 8 2 × 1 = 2 1.24 × .2_ 2 4 8 Count the number of decimal places in
both factors. There are two decimal
places in the top
factor and one more in the bottom factor. 2 + 1 = 3 The product
will have three decimal places. |
Shift the decimal point three places to
the left. 1.24 × .2_ .2 4 8 The worm crawls .248 meters. MEMORY
TRIGGERS TESTS Multiply____________________________ ___________________________________ _____________hundredths____________
Repeat_____________________________ ___________________________________ ____________________position________ ___________________________________ Speed Learning format by
Carl Peterson ©2005 |
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DIVIDING DECIMALS 1 Meaning Clusters
with decimal places move the point an equal number of spaces in
both terms. 2.56 ÷ .32 = 256 ÷ 32 = 8 Both point move two
spaces right. Think of it as multiplying the
terms by 1. Remember that 100/100
= 1. 2.56 x 100 0.32 100 The
multiplicative identity
property says that any
value multiplied by
1 remains the same. Terms with many zeros
can also be simplified. 26,000,000 ÷
13,000,000 Move the
decimal point 6 places
left. 26.000000 ÷
13.000000 = 26 ÷ 13 = 2 Always
remember to move the
point the same
direction in both terms. With decimal
points or multiple
zeros find the
easiest common place and divide. |
MEMORY
TRIGGERS TESTS _____dividing______________________ ___________________________________ ______________point_________________
________________multiplying_________ ___________________________________ Remember__________________________ ___________________________________ _____________identity________________ ___________________________________ Terms______________________________ ___________________________________ Move______________________________ ___________________________________ __________________same_____________ ___________________________________ Speed Learning format by
Carl Peterson ©2005 |