100
You must first decide how you want to round it: to the nearest unit, tens, hundreds, thousands, millions, etc., or even to the nearest multiple of 2, 5, etc.
The number 17 787 becomes 18 000 when rounded to the nearest thousand.
600
The third digit from the right is hundreds so you want to round to the two. You consider the number on the right of the two. It's five or greater so you round the two up to a three. So the final answer is 9300.
125.9 is a number. If you want to round it to the nearest whole number, it will be 126.
188.4 rounds to 188 if you want to round it to a whole number. If you want to round it to tens it would be 190. If you wanted to round it to the hundreds it would be 200.
It depends. If you want to round it to the nearest ten, it would come out as 3.80. If you want to round it tho the nearest one, you would round it to 3.85. If you want to round it to the nearest hundred or whole (I can't remember which) you would round it to 4.00. All you do is whatever way you are doing it, make sure that the number you are coming up with you can divide by five evenly. If the number you are rounding is lower than five, round down. If the number you are rounding is higher than five, round up. Hope this helps!
1000
If you want us to round a number to the nearest tenth, we'll need the number.
To round a number, the decimal place that you want to round to, needs to be specified. If you want to round to the tenths place or to 1 decimal place, then this number is already there: 7.7 is seven and seven tenths. If you want to round it to zero decimal places, or to the nearest whole number, then look at the tenths place and if it is 0-4 you round down to 7, if it is 5-9 (which it is) you round up to 8.
To the nearest 'ten' as you said, it would be: 10 To the nearest 'tenth," it would be: 8.1 To round a number, look at the number right after the number you want it to stop at. If that number is greater than 5, then you round up one digit. If it is 4 or below, the digit stays the same.
Sometimes you want to be more accurate.