5.4 x 28.7 = What is the answer
The correct answer and explanation is:
Correct Answer: 5.4×28.7=154.985.4 \times 28.7 = 154.98
300-Word Explanation:
To multiply 5.4 by 28.7, we follow basic decimal multiplication rules. First, ignore the decimals and multiply the numbers as if they are whole numbers: 54×28754 \times 287
We can break this down using long multiplication:
- Multiply 54 by 7: 54×7=37854 \times 7 = 378
- Multiply 54 by 80 (since 287 = 7 + 80 + 200, and 80 comes from the “8” in the tens place): 54×80=432054 \times 80 = 4320
- Multiply 54 by 200: 54×200=1080054 \times 200 = 10800
Now add up: 378+4320+10800=15498378 + 4320 + 10800 = 15498
Now count how many decimal places were originally in the problem:
- 5.4 has 1 decimal place.
- 28.7 has 1 decimal place.
- So, the product must have 2 decimal places.
Take 15498 and place the decimal two places from the right: 154.98154.98
Why It Works
When multiplying decimals, the position of the decimal in the result is determined after multiplication by counting the total decimal places from both numbers. This approach simplifies the process and avoids confusion, especially when using a calculator.
Real-World Example
Suppose you are buying 28.7 liters of fuel and the price per liter is $5.40. To find the total cost, you multiply: 5.4×28.7=154.985.4 \times 28.7 = 154.98
This means you’ll pay $154.98 for the fuel.
Understanding how to handle decimals in multiplication is useful in real-world budgeting, shopping, construction, and science applications.