A large number is written with a one followed by many zeros $(1000 \ldots 000)$. When 1 is subtracted from this number, the sum of the digits in the result is 252 . How many zeros are in the original number?
(A) 27
(B) 28
(C) 29
(D) 42
(E) 252
We begin by considering cases in which 1 is subtracted from numbers that start with one and are followed by smaller numbers of zeros.

| 10 | 100 | 1000 | 10000 | 100000 |
| ---: | ---: | ---: | ---: | ---: |
| -1 |  |  |  |  |
| 9 | $\frac{-1}{99}$ | $\frac{-1}{999}$ | $\frac{-1}{9999}$ | $\frac{-1}{99999}$ |

In the examples above, each result consists of $9 \mathrm{~s}$ only and the number of $9 \mathrm{~s}$ is equal to the number of zeros in the original number. Can you explain why this pattern continues as we increase the number of zeros?

Since each of the digits in the result is a 9 and the sum of these digits is 252 , then the number of $9 \mathrm{~s}$ in the result is equal to $\frac{252}{9}=28$.

The number of zeros in the original number equals the number of $9 \mathrm{~s}$ in the result, which is 28 .

ANswer: (B)