Suppose we write down the smallest positive two-digit, three-digit, and four-digit multiples of 9 What is the sum of these three numbers?
Two-digit multiple: 18
Three-digit multiple: 117
Four-digit multiples: 1116
Answer: 18 + 117 + 1116 = 1251
2-digit multiple ==18
3-digit multiple ==108
4-digit multiple ==1008
The sum ==18 + 108 + 1008 ==1,134