Transcript Section 1.4 - HarjunoXie.com

Section 1.4
Rounding and Estimating
Rounding a whole number means
approximating it.
20
23
30
23 rounded to the nearest ten is 20.
40
48
50
48 rounded to the nearest ten is 50.
10
15
20
15 rounded to the nearest ten is 20.
Martin-Gay, Prealgebra, 5ed
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Rounding Whole Numbers
to a Given Place Value
Step 1. Locate the digit to the right of the
given place value to be rounded.
Step 2. If this digit is 5 or greater, add 1
to the digit in the given place
value and replace each digit to
its right by 0.
Step 3. If this digit is less than 5, keep
the digit in the given place value
and replace each digit to its right
by 0.
Martin-Gay, Prealgebra, 5ed
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Making estimates is often the
quickest way to solve real-life
problems when their solutions do
not need to be exact.
Martin-Gay, Prealgebra, 5ed
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Helpful Hint
Estimation is useful to check for
incorrect answers when using a
calculator. For example, pressing a
key too hard may result in a double
digit, while pressing a key too softly
may result in the number not
appearing in the display.
Martin-Gay, Prealgebra, 5ed
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