Remark
I have the feeling that someone is trying to get you to round when the number you are using to round is a 5. That rounding procedure can be very complicated. And it really depends on what you have been told. So if you have any special rounding rules for question 2 and 3, please let me know. I will round them the way I would normally round them, which is to round the the same way as I would if that 5 was a six. Simple. You round up.
One
64000 rounded to the 6 = 60000. The 4 is less than 5. You round down.
Two
850,000. When you round this, you round up (by the simple rule I use which 5 and above you round up).
850000 rounded is 900000
Three
301 587 Rounds up to 302,000. But be careful that you find out your rounding rule for 5. You have 2 examples here. In question 2 the number you were rounding (8) is an even number. And in this question, the number you are rounding, is odd (1). They might have different rules.
Four
10832 rounds to 11000 the zero goes up 1 level. When you enter this question, and you get them right, all is well. If not leave a note and we'll try and work it out.