16, 81, 256, 625 all have five factors.
One possible conjecture is that each square number up to 1000 has 4 factors. The conjecture is manifestly false, but it is still a conjecture.
1001
You end up with a number that is 1000 times as large.
The maximum number of zeros in a number is determined by the number of factors of 10 in that number. Each factor of 10 is made up of 2 factors of 5 and 2 factors of 2. Therefore, the maximum number of zeros in a number is equal to the minimum of the number of factors of 5 and the number of factors of 2. For example, in the number 1000, there are three factors of 10, so the maximum number of zeros is 3.
1012
Rounding up implies the number is smaller than 1000. However, a number smaller than 1000 cannot be a 4-digit number. So there cannot be such a number. What was said is wrong. The greatest 4 digit number that rounds up is 999.9
if you have a number with a five as the last digit you round up.
270 and 1000
Look at the number in the hundreds position. It is a 5, so the number will be rounded up. So 2000 will be the answer.
500
Of the numbers up to 50, 48 has the most factors.
the 1/1000 column is the third after the decimal. Look at the fourth number after decimal. If 5 or greater, round up the thousandth column to next higher number; if less than five, keep it the same. Since the fouth number after decimal is 5, round up to 7.139