Transcript Decimals (Day 1)

Decimals (Day 1)
Place
Thousands Hundreds Tens Ones . Tenths Hundredths Thousandths
Place
Value
1,000
100
10
1
1/10
1/100
1/1000
With whole numbers and decimals, the value of each digit in a
decimal is the product of the digit and its place value
8052.468
8,000
Digit: 8
50
2
.4
.06
.008
Value: 8,000 or .008
Decimals (Day 1)
Try It:
Give the value of each 1:
Give the value of each 3:
316.24
316.24
587.13
587.13
Decimals (Day 1)
Read 8,052.468
1. Read the whole number:
“Eight thousand fifty two”
2. Read the decimal:
“and”
3. Read the decimal values (say the last value):
“four hundred sixty eight thousandths”
8,052.468 = “Eight thousand fifty two and
four hundred sixty eight thousandths”
Decimals (Day 1)
Try It:
Read: 42.68
Read: 634.16
Read: 46,600.661
Decimals (Day 1)
To compare and order decimals, write the numbers
with their decimal points lined up. Then compare the
digits in each place from left to right.
Compare 3.75 and 3. 9
3.75
3.90
3.75 < 3.9
Decimals (Day 1)
Try It:
Use < , > , = to compare each set of numbers.
387.65
387.56
17.341
17.3409
53.31
53.310
Homework: Lesson 3-1 (#31-24)
Decimals (Day 2)
Before solving an addition or subtraction
problem using decimals you may want to
estimate a solution using simpler numbers.
Example #1:
14.779 + 20.24
Round to the nearest whole numbers: 15 + 20 = 35
Estimation: 14.779 + 20.24  35
Example#2:
67.54 – 32.45
Round to the nearest whole number: 68 – 32 = 36
Estimation: 67.54 – 32.45  36
Decimals (Day 2)
Adding and Subtracting Decimals:
1. Write the numbers with their decimal point
lined up. (This lines up the place values)
2. Annex zeros as needed.
3. Add or subtract digits.
4. Place the decimal point in the answer.
Decimals (Day 2)
Example #3:
9.55 + 8.39 =
Estimate:
10 + 8  18
Solve:
9.55
+
8.39
17.94
Decimals (Day 2)
Put it all together!
Solve:
x – 4.5 = 8.6
n + 16.05 = 37.4
j + 2.75 = 11.3
k – 12.87 = 3.6
Homework: Lesson 3-3
(#2-38 evens)