Consider the expression (0.6) • (0.7). a) Write a related expression using whole number factors, then evaluate the expression. b) How many times greater is the product of your rela... Consider the expression (0.6) • (0.7). a) Write a related expression using whole number factors, then evaluate the expression. b) How many times greater is the product of your related expression from part a than the product of your original expression? Explain your thinking. c) Mai says the product of (0.6) • (0.7) is 4.2. Do you agree with Mai? Use the related expression from part a to help you determine whether Mai is correct.
Understand the Problem
The question involves evaluating the expression (0.6) • (0.7) by rewriting it using whole number factors, comparing the two products, and assessing a claim regarding the product's value.
Answer
The product of $(0.6) \cdot (0.7)$ is $0.42$.
Answer for screen readers
The value of $(0.6) \cdot (0.7)$ is $0.42$.
Steps to Solve
- Rewrite Using Whole Number Factors
To rewrite $0.6$ and $0.7$ as whole number factors, we can express them as fractions:
$$ 0.6 = \frac{6}{10} \quad \text{and} \quad 0.7 = \frac{7}{10} $$
We can then write the original expression as:
$$ (0.6) \cdot (0.7) = \left(\frac{6}{10}\right) \cdot \left(\frac{7}{10}\right) $$
- Evaluate the Expression
Next, we multiply the fractions:
$$ \left(\frac{6}{10}\right) \cdot \left(\frac{7}{10}\right) = \frac{6 \cdot 7}{10 \cdot 10} = \frac{42}{100} $$
Now, we convert this back to decimal:
$$ \frac{42}{100} = 0.42 $$
- Determine Comparison
For part b, we need to compare this product with the original expression ($0.6 \cdot 0.7$). Since we have both equal to $0.42$, we can calculate how many times greater one product is compared to the other, which is:
$$ \frac{0.42}{0.42} = 1 $$
- Evaluate Mai’s Claim
For part c, Mai claims the product is $4.2$. We need to check this claim against our previous result of $0.42$.
Since $4.2 \neq 0.42$, Mai is incorrect.
The value of $(0.6) \cdot (0.7)$ is $0.42$.
More Information
The product of two decimal numbers, $0.6$ and $0.7$, can be represented with fractions for easier calculation. By converting to fractions, we find the accurate product is $0.42$, which is significantly less than $4.2$. This illustrates the importance of careful arithmetic with decimals.
Tips
When working with decimal multiplication, a common mistake is to misunderstand the placement of the decimal point in the final product. Always verify the placement by converting to fractions or visualizing the multiplication.
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