1
1 
2
ABC 
3
DEF 
4
GHI 
5
JKL 
6
MNO 
7
PQRS 
8
TUV 
9
WXYZ 

0
0 


Digit Number 
Choices 
0 1 
1 
2 3 4 5 6 8 
3 
7 9 
4 
Where X equals the digit on the phone, and _{y} equals the current
total of numbers in the series
(starting at and incrementing by 1 for each number):
X_{y} × ... × X_{n} = Total Number of Phone Number
to Letter Conversions
