First, note that rounding up makes a number bigger and rounding down makes a number smaller. Therefore, we want to round down, as going down means that we start with a bigger number. Next, if it has to be in the nearest hundred to 700, it has to be in the 600s or 800s (as 600 and 800 are the two closest hundreds), and we have already closed off the 600s as options. When rounding to a certain digit, a rule is that if the next digit is 5 or higher, you round up. Otherwise, you round down. Therefore, as the numbers you can put into one digit are 1,2,3,4,5,6,7,8, and 9, the highest number that is under 5 is 4, making our number 84_. To fill that blank, we can select any number we want, and since we want the highest number possible, we can choose 9, making our number 849.
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