estimating sums estimation and rounding how can we use what we know about rounding to estimate?...
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42510011 0010 1010 1101 0001 0100 1011
Estimating Sums
4251
0011 0010 1010 1101 0001 0100 1011
Estimation and Rounding
How can we use what we know about rounding to estimate?
Estimating sums is best done by rounding the addends, then adding?
4251
0011 0010 1010 1101 0001 0100 1011
Estimation and Rounding
Step 1- Round the addends to the largest place value both numbers have in common.
What is the largest place value in common?
3,456 + 687
4251
0011 0010 1010 1101 0001 0100 1011
Estimation and Rounding
The hundreds place is the largest place value the two addends share in common.
3,456 + 687
4251
0011 0010 1010 1101 0001 0100 1011
Estimation and Rounding
Round both addends to the nearest hundred.
3,456 687
Use the poem to help.
Find your number.
4251
0011 0010 1010 1101 0001 0100 1011
Estimation and Rounding
Look right next door.
3,456 687
4251
0011 0010 1010 1101 0001 0100 1011
Estimation and Rounding
4 or less, just ignore.
3,456 687
Both the 5 and 8 are greater than 4, so move to the next line of the poem.
4251
0011 0010 1010 1101 0001 0100 1011
Estimation and Rounding
5 or more, add one more.
3,456 687
Both the 5 and 8 are 5 or greater, so add 1 to the numbers in the hundreds place. (4 and 6)
4251
0011 0010 1010 1101 0001 0100 1011
Estimation and Rounding
5 or more, add one more.
3,456 687
Both the 5 and 8 are 5 or greater, so add 1 to the numbers in the hundreds place. (4 and 6)
+ 1 + 1
4251
0011 0010 1010 1101 0001 0100 1011
Estimation and Rounding
3,456 687
Any number to the left remains unchanged. The 3 in 3,456 is unchanged.
+ 1 + 1
3,
4251
0011 0010 1010 1101 0001 0100 1011
Estimation and Rounding
3,456 687
Add the 1 to the place value you are rounding.
+ 1 + 1
3,5 7
4251
0011 0010 1010 1101 0001 0100 1011
Estimation and Rounding
3,456 687
All of the remaining numbers to the right become zeros.
+ 1 + 1
3,5 7 0000
4251
0011 0010 1010 1101 0001 0100 1011
Estimation and Rounding
Finally, add the rounded numbers.
3,500 + 700 4,200
4251
0011 0010 1010 1101 0001 0100 1011
Estimation and Rounding
The estimate is about 4,200.
3,456 + 687
4,200
4251
0011 0010 1010 1101 0001 0100 1011
5-2 Estimating Sums and Differences
ExampleSusan is worried that she has spent too much money. She has $256 in her checking account and has written checks for $92.69, $126.58, $9.58, and $12.39.Determine if Susan has spent too much money.
4251
0011 0010 1010 1101 0001 0100 1011
5-2 Estimating Sums and Differences
ExampleSusan is worried that she has spent too much money. She has $256 in her checking account and has written checks for $92.69, $126.58, $9.58, and $12.39.Determine if Susan has spent too much money.
Round each check to the nearest dollar amount.
4251
0011 0010 1010 1101 0001 0100 1011
5-2 Estimating Sums and Differences
ExampleSusan is worried that she has spent too much money. She has $256 in her checking account and has written checks for $92.69, $126.58, $9.58, and $12.39.Determine if Susan has spent too much money.
Round each check to the nearest dollar amount. 92.69
4251
0011 0010 1010 1101 0001 0100 1011
5-2 Estimating Sums and Differences
ExampleSusan is worried that she has spent too much money. She has $256 in her checking account and has written checks for $92.69, $126.58, $9.58, and $12.39.Determine if Susan has spent too much money.
Round each check to the nearest dollar amount. 92.69
4251
0011 0010 1010 1101 0001 0100 1011
5-2 Estimating Sums and Differences
ExampleSusan is worried that she has spent too much money. She has $256 in her checking account and has written checks for $92.69, $126.58, $9.58, and $12.39.Determine if Susan has spent too much money.
Round each check to the nearest dollar amount. 92.69
4251
0011 0010 1010 1101 0001 0100 1011
5-2 Estimating Sums and Differences
ExampleSusan is worried that she has spent too much money. She has $256 in her checking account and has written checks for $92.69, $126.58, $9.58, and $12.39.Determine if Susan has spent too much money.
Round each check to the nearest dollar amount. 92.69
4251
0011 0010 1010 1101 0001 0100 1011
5-2 Estimating Sums and Differences
ExampleSusan is worried that she has spent too much money. She has $256 in her checking account and has written checks for $92.69, $126.58, $9.58, and $12.39.Determine if Susan has spent too much money.
Round each check to the nearest dollar amount. 92.69
241
4251
0011 0010 1010 1101 0001 0100 1011
5-2 Estimating Sums and Differences
ExampleSusan is worried that she has spent too much money. She has $256 in her checking account and has written checks for $92.69, $126.58, $9.58, and $12.39.Determine if Susan has spent too much money.
Round each check to the nearest dollar amount. 92.69
241
Since 241 < 256, Susan has enough money in her account.
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