Final answer:
To estimate the difference by rounding each number to the nearest ten thousand, round 737,478 to 740,000 and 18,300 to 20,000. Subtract the rounded numbers to find the estimated difference: 740,000 - 20,000 = 720,000.
Step-by-step explanation:
To estimate the difference by rounding each number to the nearest ten thousand, we round 737,478 to 740,000 and 18,300 to 20,000. Then, we subtract these rounded numbers to find the difference: 740,000 - 20,000 = 720,000. Therefore, the estimated difference is 720,000.