Round off to the nearest hundred then subtract 999 999 – 899 999
The Correct Answer and Explanation is:
Correct Answer:
999,999 rounded to the nearest hundred is 1,000,000
899,999 rounded to the nearest hundred is 900,000
Now subtract: 1,000,000 – 900,000 = 100,000
Explanation
Rounding to the nearest hundred involves changing a number so that it ends in two zeros, depending on the value of the tens digit. If the tens digit is 5 or more, the number is rounded up to the next hundred. If the tens digit is 4 or less, the number is rounded down.
First, examine the number 999,999. Focus on the last three digits which are 999. The tens digit here is 9, which is greater than 5. This means rounding up is needed. The number then becomes 1,000,000 when rounded to the nearest hundred.
Next, consider the number 899,999. Again, the last three digits are 999. The tens digit is also 9, so this number must also be rounded up. Rounding it to the nearest hundred gives 900,000.
After rounding both numbers, the subtraction becomes simple. Subtract 900,000 from 1,000,000:
1,000,000
– 900,000
= 100,000
This is the rounded difference between the two original numbers.
Rounding before performing arithmetic operations is helpful when estimating or simplifying complex problems. It provides a quick and close approximation without needing the exact numbers. In real-life scenarios such as budgeting, estimating population changes, or checking rough totals, rounding plays a key role.
Although the original numbers differ by exactly 100,000 even without rounding, this example demonstrates how rounding supports mental math and quick decisions. It also confirms that small changes from rounding do not always significantly affect the result when the difference is large. However, in some cases, rounding might slightly alter the final value, so it is important to know when an estimate is acceptable and when an exact value is necessary.
