I am not quite sure what you mean by the "lowest hundred" (or lowest hunderd, even). To the nearest hundred, it would be 549.99... recurring.
549
49 lowest no. 45
500
The largest integer that, when rounded to the nearest hundred, would round to 500, is 549.
The smallest one is 550,000 . The largest one is 649,999 .
7649
750
It is 549.
The lowest number that rounds to 700 to the nearest hundred would be 650.
49 lowest no. 45
600
The largest number that round to 0 when when rounding to the nearest hundred (100) is 49.The smallest would be 1 if we consider whole numbers only.
500
The largest integer that, when rounded to the nearest hundred, would round to 500, is 549.
The smallest number that is 600 when rounded to the nearest hundred is 550. The largest number that is 600 when rounded to the nearest hundred is 649.
The smallest one is 550,000 . The largest one is 649,999 .
To the nearest hundred it will round down to zero.
Half of 100 is 50, so the largest number that ought to round to 400 to the nearest 100 would be 400 + 50 = 450; however, numbers exactly half way round up, so the largest whole number that rounds to 400 is one less than this, namely 450 - 1 = 449.