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To divide a decimal by a whole number, simply divide as usual. PLACE THE DECIMAL POINT in the quotient (the answer) DIRECTLY ABOVE its place in the dividend (the number being divided).
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Welcome Activity
Estimate:1) 25 ÷ 4.7
2) 40.79 ÷ 7
3) 984.76 ÷ 38.1
5
6
25
10/1/2015 1-2 C Divide Decimals
• To divide a decimal by a whole number, simply divide as usual.
• PLACE THE DECIMAL POINT in the quotient (the answer) DIRECTLY ABOVE its place in the dividend (the number being divided).
Example 1Find 45.9 3
Estimate 45 ÷ 3 = 15
1
– 31 5
5
– 150 9
– 90
.3
45.9 ÷ 3 = 15.3; Compared to the estimate, the quotient is reasonable.
Example 2Find 8.69 22
Place the decimal point.0.
– 6 62 0 9
3
– 1 9811 0 Annex a zero and continue dividing.
– 1100
950
Estimate
8.69 ÷ 22 = 0.395; Compared to the estimate, the quotient is reasonable.
Example 3Owen is purchasing lumber to build a porch. The table shows the cost of the boards. If Owenbuys a 12-foot board, how much does it cost per foot?
Example 3To find the cost per foot, divide $6.48 by 12.
Place the decimal point.0.
– 6 04 8
5
– 480
4
The cost of the board is $0.54 per foot.
Example 4Violeta and her sister are sharing the cost of a digital camera. The camera costs $88.50. If Violeta saved $50 to buy the camera, how much does her sister have left after paying her share of the camera?
Estimate $90 ÷ 2 = 45; $50 – $45 = 5 Step 1 Determine how much Elena will pay for the
camera.
Example 4
Place the decimal point..
– 80 8
4
– 80 5
– 4
4 2
10– 10
0
5
Example 4
$50.00– $44.25
$5.75
$50.00 – $44.25 = $5.75
Violeta has $5.75 left.
Your Turn1) Five dozen eggs cost $10.50. Find the cost of
one dozen. How much change will you receive if you pay for one dozen eggs with a five dollar bill?
2) Meg is purchasing lumber to build a porch. The table shows the cost of the boards. If Meg buys a 10-foot board, how much does it cost per foot?
3) 1.25 ÷ 5
$3.90
$0.58
0.25
@ Home
• Decimal Division W.S. I