Final answer:
To multiply 394 by 672, we can use a round estimation. Rounding 394 to 400 and 672 to 700, the calculation becomes 400 times 700, which is equivalent to multiplying 4 hundreds by 7 hundreds. The result is 28 ten thousands.
Step-by-step explanation:
To multiply 394 by 672, we can use a round estimation. We can round 394 to 400 and 672 to 700, which gives us 400 times 700. This calculation is equivalent to multiplying 4 hundreds by 7 hundreds, which gives us 28 ten thousands. Therefore, 394 multiplied by 672 is approximately equal to 28 ten thousands.