BHSNTTSPAZ

DILBTEAIRU

DSLEATIEDW

CAMUHIRLCZ

CTAMASAHLY

AWETOTNTEV

EHSSLLRAOX

DTERLEEBRW

Rearranging the rows so that the first letters are in alphabetical order gives:

A  W  E  T   O  T  N  T  E  V
B  H   S  N  T   T  S  P  A  Z
C  A   M  U  H  I  R  L  C  Z
C  T   A  M  A  S  A  H  L  Y
D  I   L   B  T  E  A  I   R  U
D  S  L   E  A  T   I  E  D  W
D  T  E   R  L   E  E  B  R  W
E  H  S   S  L  L   R  A  O  X

Reading down the columns (ignoring the first) gives the question:

WHAT IS THE SMALLEST NUMBER SO THAT ALL

The next part is still mixed up, so rearrange the last column into reverse alphabetical order, to get:

C  A   M  U  H  I  R  L  C  Z
B  H   S  N  T   T  S  P  A  Z
C  T   A  M  A  S  A  H  L  Y
E  H  S   S  L  L   R  A  O  X
D  T  E   R  L   E  E  B  R  W
D  S  L   E  A  T   I  E  D  W
A  W  E  T   O  T  N  T  E  V
D  I   L   B  T  E  A  I   R  U

Reading down from the middle column gives:

ITS LETTERS ARE IN ALPHABETICAL ORDER

So the question is, "What is the smallest number so that all its letters are in alphabetical order?"

Checking the numbers one to twelve:

One - x
Two - x
Three - x
Four - x
Five - x
Six - x
Seven - x
Eight - x
Nine - x
Ten - x
Eleven - x
Twelve - x

None of the numbers thirteen to nineteen will work, because the "teen" section is not in alphabetical order. Therefore, the number must be an integer multiple of ten, because all other numbers will contain the numbers one to nine at some point. Neither twenty nor thirty satisfy this, but forty does. So the answer is forty.