Download Lesson 3-2

Lesson 3-2
Example 1 Multiply a Decimal by a Whole Number
Find 2.46  3.
Method 1: Use estimation.
2.46
Estimate 2.46  3  2  3 or 6
 3
7.38
Since the estimate is 6, place the decimal point after the 7.
Method 2: Count decimal places.
2.46  2 decimal places
 3
7.38  2 decimal places
Example 2 Real-World EXAMPLE
EXERCISE A bicyclist travels 0.007 miles every second. Find the distance that the
bicyclist travels in 8 seconds.
0.007
 8
0.056
There are 3 decimal places.
Remember to annex a zero.
After 8 seconds, the bicyclist travels 0.056 mile.
Example 3 Multiply Decimals
Find 0.8  0.6.
Method 1: Use estimation
0.8
Estimate 0.8  0.6 ≈ 1  1 or 1
 0.6
0.48
Since the estimate is 1, place the decimal point before the 4.
Method 2: Count decimal places.
0.8 
1 decimal place
 0.6  + 1 decimal place
0.48
2 decimal places
Example 4 Multiply Decimals
Find 6.14  4.3.
Estimate 6.14  4.3  6  4 or 24
6.14  2 decimal places
 4.3  + 1 decimal place
1842
+2456
26.402  3 decimal places
Example 5 Real-World EXAMPLE
GROCERY SHOPPING The prices of different deli meats are listed in the table. To the
nearest cent, what is the total cost of 1.75 pounds of turkey and 0.95 pounds of roast beef?
Turkey
4.89
 1.75
2445
3423
489
8.5575
Deli Prices
Meat
Price ($/lb)
Ham
3.89
Roast Beef
3.75
Turkey
4.89
Roast Beef
 2 decimal places
3.75  2 decimal places
 + 2 decimal places
 0.95  + 2 decimal places
1875
3375
3.5625  4 decimal places

4 decimal places
To the nearest cent, the turkey costs $8.56 and the roast beef costs $3.56. The total cost is $8.56
+ $3.56 or $12.12.