- Order of Operations With Whole Numbers and Exponents: Basic
- Order of Operations With Whole Numbers and Grouping Symbols
- Order of Operations With Whole Numbers
- Introduction to Order of Operations
- Comparing Numerical Expressions With Parentheses
- Introduction to Parentheses
- Power of 10: Negative Exponent
- Power of 10: Positive Exponent
- Introduction to Exponents
- Writing Expressions Using Exponents
- Estimating a Quotient of Whole Numbers
- Estimating a Product of Whole Numbers
- Estimating a Difference of Whole Numbers
- Estimating a Sum of Whole Numbers
- Rounding to Thousands, Ten Thousand, or Hundred Thousand
- Rounding to Hundreds or Thousands
- Rounding to Tens or Hundreds
- Ordering Large Numbers
- Comparing a Numerical Expression With a Number
- Introduction to Inequalities
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Estimating a Product of Whole Numbers
The whole numbers are first rounded as specified, i.e., rounded to the nearest ten, hundred and so on. Then the product of the rounded whole numbers is found to estimate the product of whole numbers.
Estimate the product 573 × 94 by first rounding each number so that it has only one non-zero digit.
Solution
Step 1:
We round each number such that it has only one non-zero digit
573 is a three-digit number. So its first digit is going to be the only non-zero digit and the other two digits would be zeros. It means rounding to nearest hundred. Since the tens digit, 7 is greater than 5, we round up 57?3 to 600.
Step 2:
94 is a two-digit number. Its first digit is going to be the only non-zero digit and the other digit would be zero. It means rounding to nearest ten. Since the ones digit, 4 is less than 5, we round down 94 to 90.
Step 3:
The estimate of the product after rounding
= 600 × 90 = 54,000
Estimate the product 2092 × 167 by first rounding each number so that it has only one non-zero digit.
Solution
Step 1:
We round each number such that it has only one non-zero digit
2092 is a four-digit number. So its first digit is going to be the only non-zero digit and the other three digits would be zeros. It means rounding to nearest thousand. Since the hundreds digit, 0 is less than 5, we round down 2092 to 2000.
Step 2:
167 is a three-digit number. Its first digit is going to be the only non-zero digit and the other two digits would be zero. It means rounding to nearest hundred. Since the tens digit, 6 is greater than 5, we round up 167? to 200.
Step 3:
The estimate of the product after rounding
= 2000 × 200 = 400,000