- Ordering Rounding and Order of Operations
- Introduction to Inequalities
- Comparing a Numerical Expression With a Number
- Ordering Large Numbers
- Rounding to Tens or Hundreds
- Rounding to Hundreds or Thousands
- Rounding to Thousands, Ten Thousand, or Hundred Thousand
- Estimating a Sum of Whole Numbers
- Estimating a Difference of Whole Numbers
- Estimating a Product of Whole Numbers
- Estimating a Quotient of Whole Numbers
- Writing Expressions Using Exponents
- Introduction to Exponents
- Power of 10: Positive Exponent
- Power of 10: Negative Exponent
- Introduction to Parentheses
- Comparing Numerical Expressions With Parentheses
- Introduction to Order of Operations
- Order of Operations With Whole Numbers
- Order of Operations With Whole Numbers and Grouping Symbols
- Order of Operations With Whole Numbers and Exponents: Basic
Estimating a Difference of Whole Numbers
The whole numbers are first rounded as specified, i.e., rounded to the nearest ten, hundred and so on. Then the difference of the rounded whole numbers is found to estimate the difference of whole numbers.
Estimate the difference 6,57󠄀3 − 4,536 by first rounding each number to the nearest hundred.
In 6,573, the tens digit, 7 is greater than 5. So we round up 6,573 to the nearest hundred as 6,600.
In 4,536, the tens digit, 3 is less than 5. So we round down 4,536 to nearest hundred as 4,500.
So the estimated difference is 6,600 − 4,500 = 2,100.
Estimate the difference 44,904 − 23,091 by first rounding each number to the nearest thousand.
In 44,904, the hundreds digit, 9 is greater than 5. So we round up 44,904 to the nearest thousand 45,000.
In 23,091, the hundreds digit, 0 is less than 5. So we round down 23,091 to nearest thousand 23,000.
So the estimated difference is 45,000 − 23,000 = 22,000
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