Download - Review Rounding Write & Evaluate Expressions
100,000,000,000 10,000,000,000 1,000,000,000 100,000,000 10,000,000 1,000,000 100,000 10,000 1,000 100 10 1 . .1 .01 .001 .0001 .00001
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4 5 9 2 6 1 2 4 0 1 2 5 . 4 6 3 7 8
<--Whole NumbersPart of one (1)->
Equivalent Fraction-> n/10 n/100 n/1000 n/10,000 n/100,000
Find the Place Value and Round
Where do I look first?
• Round this number to the nearest hundred
368
ActionIncrease by one or stays the same
Look at the number to
the right of the action
Use rounding
• When the question asks you to estimate.
Such as:“about how many”…?
When an exact answer isn’t possible. When an answer is difficult to obtain.
(Educated guessing for multiple choice)
Rounding Procedures
1. Draw an arrow pointing to the place you are rounding. (action)
2. Draw a dot (an eye) under the digit to the right of the place you are rounding.
3. If the digit is 0-4, the number with the arrow stays the same. The rest of the numbers to the right change to 0’s.
Rounding Procedures
4. If the digit is 5-9, the number with the arrow rounds up one. The rest of the numbers to the right turn to 0’s.
Rounding Rhyme
• Mark the place,• Look to the right• Four or less are out of sight
• Five and up• Will buy one more,• All those less, are out the door
• In those empty• Right-hand spaces,• Zeros keep the proper places
• Except in places less than a whole • Such as the decimal case • The last number is the last place
5,621
Ut ohhh!
5,621
Oh yea! I’m moving up Wahoo!
6,000
5620
Every place to the right of the arrow changes to zeros
2.88 2.9
No zero place holder for me
Round 2,593, 672 to the nearest tens place.
672 2,593,
1-4 stay down
5-9 round up one
Answer 2,593,670
43.27 .5
0549.239 .4
3259.289,5 .3
345,072,749,923 .2
499 .1
Round each number to the place that has an arrow.
500
923,749,100,000
5,289
239.1
30
Practice Rounding
1) 269 (tens)
2) 2.98 (ones)
3) 3,146 (tens)
4) .912 (hundredths)
5) 86,574 (ten thousands)
6) 178.54 (hundreds)
7) 411,990 (hundreds)
Answers
1) 269 (tens)
2) 2.98 (ones)
3) 3,146 (tens)
4) .912 (hundredths)
5) 86,574 (ten thousands)
6) 178.54 (hundreds)
7) 411,990 (hundreds)
3
3,l50
.91
90,000
200.00
270
412,000
Answers
• 60• 870 or 900• 490 or 500• 650 or 700• 960 or 1,000• 200• 680 or 700
• 64• 873• 491• 652• 957• 203• 684
Estimate Sums & Differences
• Round off both numbers then add or subtract.
55 + 61 = ?
60 + 60 = 120
691 – 54 = ?
700 – 50 = 650
Math Words
• Place-The position of a digit in a number.
• Value- The product of a digit multiplied by its place.
• Standard Form-The usual way to write a number
• Expanded Form-A way to write a number as a sum of the products of each digit and its place.
• Whole number-any one of the numbers 0, 1, 2, 3, 4, and so on.
Math Words
• Decimal-A number with one or more digits to the right of the decimal point.
• Equivalent decimals- Decimals that name the same number such as .4, .40, .400
• Round-To find the nearest value of a number, based on the given place.
• Estimate-To find a number that is close to the exact answer.
• Variable-A symbol used to represent a number or numbers
Math Words
• Algebraic Expression - A variable by itself or
a combination of one or more variables, one or more operations, and possibly one or more numbers such as
n + 2
• Evaluate or evaluation - To find the value of an expression by performing the operation or operations.
For Examplen = 3, n + 2 3 + 2 = 5