650. Although acccording to the "round-to-even" rule, (for example the IEEE 754 standard for rounding), it would be a 650 would be rounded down to 600 but 650 plus a tine bit would be rounded up to 700.
7550 is the smallest number than rounds to 7600 when rounded to the nearest hundred.
500
849 is the highest number that rounds to 800.
1450
2999
The lowest number that rounds to 700 to the nearest hundred would be 650.
7550 is the smallest number than rounds to 7600 when rounded to the nearest hundred.
7200
The number 370.14 rounds up to 400 to the nearest hundred.
8600
the lowest possible whole number is 150,000
Half of 100 is 50, so the smallest number that rounds to 400 to the the nearest hundred is 400 - 50 = 350.
3200
500
Anything from 755 to 764
200
749