To multiply factors of 10 (that's anything with zero on the end) just multiply the numbers that are NOT zeros on the end and then add the zeros back onto the answer. For example..
500 × 3
multiply 5 × 3 = 15 then add the 2 zeros back 1,500.
Your problem is 9 × 1000
9 × 1 = 9
add the three zeros back
9,000.
