An easy way is to multiply 9 by factors of 10 10 100 1000 9 times 10=90 9 times 100=900 9 times 1000=9000 and so on
or you could find multipules of 9 that are over 27 multipulse are 9,18,27,36,45,54,63,72,81,90,99,108,117,126,135,144,153,162,171,180,189,198,207,216, etc so basically you could use any number in that list from 27 and after