Transcript Rounding Whole Numbers Through Millions

ESTIMATION AND
ROUNDING
Rounding two-digit numbers
RULES FOR ROUNDING
Two-digit number will be
1.
rounded to the nearest
ten.
Underline the number in the place
value you will round.
2.
26
Look at the number to the right of the
underlined number.
3.
30
If the number to the right is 0, 1,
2, 3, or 4, then the underlined
number stays the same.
4.
So we can say that th
closer to 30 than to 20.
5.
If the number to the right is 5, 6, 7,
8, or 9, then the underlined number
needs to go up one more number.
Every number to the right of the
underlined number becomes a zero.
Rounding three-digit numbers
RULES FOR ROUNDING
Three-digit number
1. Underline the number in the
will be rounded to
place value you will round.
the nearest
2. Look at the number to the right
hundred.
of the underlined number.
3.
520
500
So we can say that the
number 520 is closer to
500 than to 600.
If the number to the right is 0, 1,
2, 3, or 4, then the underlined
number stays the same.
4.
5.
If the number to the right is 5, 6,
7, 8, or 9, then the underlined
number needs to go up one more
number.
Every number to the right of the
underlined number becomes a zero.
26 is closer to 30 than to 20.
26
20
30
520 is closer to 500 than to 600.
50
0
520
600
Estimating sums
First, round all the numbers using the RULES
FOR ROUNDING .Then, perform the
operations.
12
+ 8
-------
10
+ 10
------20
Estimating differences
First, round all the numbers using the RULES
FOR
ROUNDING. Then, perform the operations.
-
250
- 110
------
300
- 100
------200
Now you practice.
Round these numbers.
25
78
36
158
689
324
30
80
40
200
700
300
Rounding Whole Numbers
Through Millions
By Mr. Bales
Objective
» You will be able to round whole numbers
through the millions to the nearest 10, 100,
1,000, 10,000, or 100,000
Problem
» Each year immigrants from around the
world come to the United States. In
2003, California schools welcomed
175,090 immigrant students.
» What is 175,090 rounded to the nearest
thousand?
Let’s Hear a Song About
Rounding!!
By Mr. Bales
Let's Watch Mr. Parsons!!
How To Round
» Let’s look at this number 175,090.
» First, underline the place value that you want
to round.
» Then, look at the digit to the right. If the digit
is 4 or less, the digit in the rounding place
stays the same.
» If the digit to the right is 5 or more. The digit
in the rounding place increases by one.
» Last, change all the digits to the right of the
rounding place to zero.
Game Time!!
» Round to the nearest »
hundred
» 71,105
»
» 654,354
»
» 678,947
» Round to the nearest »
ten thousand
»
» 1,256,876
»
» 23,786,983
Round to the
nearest hundred
thousand
234,654,899
3,853,216
Round the nearest
million
34,652,985
976,634,321
Your turn!
Your turn!
Estimate each product,
addition and subtraction.
» 1. 62 X 82
2. 59 X 48
3. 74 X 302
» 4681+9284
» 3177 - 1294
2848+8352
» 4.324587-52418