Rounding Numbers
to the
Nearest Hundred
by Mrs. Zagrodny
When you find the
hundred that is closest
to a number, you are
rounding
.
For example, 400 is the
closest ten to 360.
So, 360 to the nearest 100 is
rounded to 400.
Again, let’s think about a
number line like a
roller coaster.
You might think about a
number line that looks
like this:
100
200
300
On this number line, what
number would come half way
between 100 and 200?
150
100
200
300
What number would come half
way between 200 and 300?
150
100
250
200
300
What hundred would be next?
What number would be half
way between?
150
100
250
200
350
300
400
100
Can you guess about
where 170 would be on
this number line?
150
250
350
170
200
300
40
100
If the roller coaster
stopped, what number
would it roll to?
150
250
350
170
200
300
400
100
Can you guess about
where 230 would be on
this number line?
150
350
250
230
200
300
400
100
If the roller coaster
stopped, what number
would it roll to?
150
250
350
230
200
300
400
Can you guess about
where 360 would be on
this number line?
150
250
350
360
100
200
300
400
100
What would you round it to?
150
250
350
360
200
300
400
Can you guess about
where 410 would be on
this number line?
150
250
350
410
100
200
300
400
100
What would you round it to?
150
250
350
410
200
300
400
100
Can you guess about
where 190 would be on
this number line?
150
250
350
190
200
300
400
100
Can you guess about
where 190 would be on
this number line?
150
250
350
190
200
300
400
100
What would you round it to?
150
250
350
190
200
300
400
What about a number like 250?
It’s right in the middle!
100
150
250
200
350
300
40
100
Our rule is to round to the next
hundred.
150
250
200
350
300
400
Tell a number that would
round to 100.
150
140
130
120
110
100
200
250
350
300
40
When you round to the nearest
hundred, look in the tens place.
If it has 1,2,3, or 4 round down.
If it has 5, 6 ,7, 8, or 9 round up.
To round remember this rhyme,
5, 6, 7, 8, 9
GO UP all the time!!
Rounding numbers is so fun,
We will do it 'till we're done.
If a number's 1-4,
Round it down right through the floor.
If a number's 5-9,
Round it up it is just fine.
Round up,
Round down,
1,2,3,4 --- 1-2, 3-4
Now it’s your turn!
You can get some help from
the number line.
What hundred is
closest to
560?
Put your bean on the closest
hundred.
What hundred is
closest to
790?
Put your bean on the closest
hundred.
What hundred is
closest to
830?
Put your bean on the closest
hundred.
What hundred is
closest to
990?
Put your bean on the closest
hundred.
What hundred is
closest to
650?
Put your bean on the closest
hundred.
What hundred is
closest to
940?
Put your bean on the closest
hundred.
Are you roller
coaster ready
for an
assignment?