Understand that metric prefixes represent specific powers of ten, which scale the base unit by a certain factor.
Recall that 'kilo-' corresponds to a factor of 10^3, which means it multiplies the base unit by 1000.
Recognize that 'mega-' corresponds to 10^6 (one million), 'centi-' corresponds to 10^-2 (one hundredth), and 'milli-' corresponds to 10^-3 (one thousandth).
Compare each prefix's factor to the number 1000 to identify which one matches exactly.
Conclude that the prefix indicating a factor of 1000 is 'kilo-'.