What is 9,921 round to the nearest hundred

9,900 because u would see if 2 is greater than 5 which it's not so because the nine was in the hundreds spot you keep it the same and make everything behind it 0

The answer is 9,900. If you look at the hundreds place (the second 9) and then look at the two numbers behind it, you will see that the last two numbers are 21. The rule for rounding is, "If the number is above 5, you round up. If the number is below 5, then you round down". So since 21 is less that 50 (multiply 5 by ten, hundred, etc.) You round down. So the answer is 9,900