<PRE><B>Question 438433</B>
(1)
None of the digits can be {{{3}}}, {{{2}}}, or {{{1}}}, since
the sum of any arrangement of {{{399}}} is too small {{{3 + 9 + 9 = 21}}}
What is left is all possible arrangements of:
994
985
976
886
877
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The arrangements are:
994
949
499 - 3 possible
---
985
958
895
859
598
589 - 6 possible
---
976 - 6 possible
886 - 3 possible
877 - 3 possible
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There are 21 3-digit numbers whose digits add up to 22


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