An infinite number.
600
There are more than 5 numbers that can round down to 600 if rounding by hundreds. When rounding down by hundreds anything 601-649 rounds down to 600. If you're rounding by tens it would be anything 600-604.
0
There are 600 5-digit numbers divisible by 150.
Just 1 and 5.
600
70
600
600
649 rounded to the nearest hundreds place value would be 600.
600
It is 600 rounded to the nearest hundred