53,000 rounded to the nearest ten thousand is

53,000 rounded to the nearest ten thousand is 50,000

the number value in the ten thousandth place is 5. So, when you round a number, you look at the number before the number of the given place value. In this case, the number before the number of the given place value is 3.
Now,
when you round a number, if the number before the number of the given place value is 5 or greater than 5, you add 1 to that number, but if is less than 5, you leave it by itself. 
In this case, 3 is less than 5, So, we leave the 5 by itself. and add 4 zeros.

Number nine is f(x)= 40x : ) hoped i ya