Transcript Step 1

© 2007 M. Tallman
Step 1: Circle the
digit in the place
that you must round
to.
Step 2: Draw an
arrow to the place
on the right.
Round to the nearest one (units).
7.23
Findright
yournext
number.
Look
door.
© 2007 M. Tallman
Step 1: Circle the
digit in the place
that you must round
to.
Step 2: Draw an
arrow to the place
on the right.
Round to the nearest tenth.
Step 3: If the
number is four or
less, then the
circled number
stays the same.
00
7 .2
3
Step 4: All
numbers to the
right of the circled
number become
zeros, or disappear.
Just
Ignore!
2 is less
than 4
4 or less, just ignore.
© 2007 M. Tallman
7.23 rounded to the
nearest one (unit) is…
7
7.23
7
8
7.23 is closer to 7 on the number line.
© 2007 M. Tallman
Step 1: Circle the
digit in the place that
you must round to.
Step 2: Draw an
arrow to the place on
the right.
Round to the nearest one (units).
5 .7
Findright
yournext
number.
Look
door.
© 2007 M. Tallman
Step 1: Circle the
digit in the place that
you must round to.
Step 2: Draw an
arrow to the place on
the right.
Round to the nearest one (units).
Step 3: If the
number is four or
less, then the circled
number stays the
same.
Step 4: If the
number is 5 or
greater, then add 1 to
the circled number.
Step 5: All numbers
to the right of the
circled decimal
number become
zeros, or disappear.
5 .0
6
7
5+1=6
7 is not
less
than 4
54 or
or more,
less, just
add 1
ignore.
more.
© 2007 M. Tallman
5.7 rounded to the
nearest one (unit) is…
5
6
5.7
5.7 is closer to 6 on the number line.
© 2007 M. Tallman
6
17.4 - 4.8
The actual
answer is 12.6, so
our estimation is
pretty accurate.
17 - 5 = 12
Step 1:
Rounding is
always first.
Decide which
place to round to.
Step 2:
Round each
number to the
nearest whole
number.
© 2007 M. Tallman
Step 3:
Now you can
subtract 17
and 5
mentally.
15.7 - 7.8
The actual
answer is 7.9, so
our estimation is
pretty accurate.
16 - 8 = 8
Step 1:
Rounding is
always first.
Decide which
place to round to.
Step 2:
Round each
number to the
nearest whole
number.
© 2007 M. Tallman
Step 3:
Now you can
subtract 18
and 8
mentally.
45.8 - 6.3
The actual
answer is 39.5,
so our estimation
is pretty
accurate.
46 - 6 = 40
Step 1:
Rounding is
always first.
Decide which
place to round to.
Step 2:
Round each
number to the
nearest whole
number.
© 2007 M. Tallman
Step 3:
Now you can
subtract 46
and 6
mentally.
Estimate Each Difference
1. 19.76 - 9.55
20 - 10 = 10
2. 9.45 - 8.56
9 - 8 =1
3. 14.7 - 8.3
15 - 8 = 7
4. $23.87 - $6.70
$24.00 - $7.00 = $17.00
© 2007 M. Tallman
Estimate Each Difference
5. 13.56 - 4.4
14 - 4
= 14
6. 9.78 - 5.89
10 - 6 = 4
7. $9.33 - $2.59
$9.00 - $3.00
= $6.00
8. $14.77 - $8.70
$15.00 - $9.00 = $6.00
© 2007 M. Tallman
Estimate Each Difference
9. $23.26 - $14.67
$23.00 - $15.00 = $8.00
10. 66.42 - 33.31
66 - 33 = 33
11. $29.53 - $2.45
$30.00 - $2.00 = $28.00
12. 12.23 - 0.67
12 - 1 = 11
© 2007 M. Tallman