To get the answer to this question, knowledge of how to round is needed.
43.586 has numbers in the tens, hundreds, and thousandths place, after the decimal.
To round a number, you must look at the number that comes after it and ask 'is this number (in this case, 6) 5 or higher?'
if the answer is 'yes' (in this case, it is) then you take the number that comes before it, and increase it by 1.
So the answer to your question is 43.59 :)