Transcript Lessons 3.1 Rounding and Estimating

Lessons 3.1
Rounding and Estimating
Place value
Rounding Decimals
• Check _____________
_____________________
______________.
• If it’s ______________
______________.
• If it’s ______________
____________.
CU 1: Identify the underlined place.
Then round each number to that place.
• 38.41
• 0.772
• 5.025
• 9.8517
New symbol
• When we estimate, we say our answer is
__________________ to a certain value.
• The symbol for “approximately equal to” is:
Round to estimate
• Round all numbers to same place, then add.
• Example: 8.71 
•
3.21 
•
+ 13.899 
Front-end estimate
A _________________ is often closer to the exact sum.
First ____________________. Then ______ to estimate
the sum of the remaining digits. Then ____________
___________________.
Example: $6.04 
$3.45 
+ $4.43 
Estimate by Clustering
You can also use _______________ to estimate
the sum of several numbers that are __________
__________________.
Example: $9.50
$8.45
+ $9.08
CU 2
a. Round 8.7398 to the nearest tenth.
b. Round 8.7398 to the nearest integer.
CU 3: Estimate to find whether each
answer is reasonable.
• Calculation:
Calculation:
CU 4:Use front-end estimation to estimate the
total cost of the fruit.
The bananas cost $1.32, the apples cost $2.19,
and the avocados cost $1.63.
CU 5:
Estimate the total electricity charge:
• March: $81.75
• April: $79.56
• May: $80.89
Tonight’s Assignment
• PM 3.1: column 1
• Inequality Review Wkst. all