Multiplication Estimates
1. **Problem:** Calculate the products and estimate ranges for the following multiplications:
2. **Calculate $24.09 \times 12.57$:**
- Approximate $24.09 \approx 24$ and $12.57 \approx 13$.
- Multiply the approximations: $24 \times 13 = 312$.
- Now calculate the exact product:
$$24.09 \times 12.57 = 302.8713$$
- So, the exact answer is $302.8713$, close to the estimate $312$.
3. **Calculate $3.29 \times 3.81$:**
- Approximate $3.29 \approx 3$ and $3.81 \approx 4$.
- Multiply the approximations: $3 \times 4 = 12$.
- Use the breakdown given:
- $3 \times 3 = 9$
- $8 \times 2 = 16$
- $9 \times 1 = 9$
- Calculate the exact product:
$$3.29 \times 3.81 = 12.5349$$
- The exact answer $12.5349$ is close to the estimate $12$.
4. **Calculate $4.1 \times 13.5$:**
- Approximate $4.1 \approx 4$ and $13.5 \approx 13$.
- Multiply the approximations: $4 \times 13 = 52$.
- Add the extra part:
- $5 \times 1 = 5$
- Calculate the exact product:
$$4.1 \times 13.5 = 55.35$$
- The exact answer $55.35$ is close to the estimate $52 + 5 = 57$.
5. **Calculate $16.12 \times 3.55$:**
- Approximate $16.12 \approx 16$ and $3.55 \approx 4$.
- Multiply the approximations: $16 \times 4 = 64$.
- Calculate the exact product:
$$16.12 \times 3.55 = 57.226$$
- The exact answer $57.226$ is slightly less than the estimate $64$.
**Summary:**
- $24.09 \times 12.57 = 302.8713$
- $3.29 \times 3.81 = 12.5349$
- $4.1 \times 13.5 = 55.35$
- $16.12 \times 3.55 = 57.226$
Estimation helps to quickly find a range for the product before calculating the exact value.