1. UPC detective: find the missing number in each of these UPC codes:
Code |
missing digit
|
|
A. ?-78787-03104-3 |
0 |
|
B. 0-?0735-00458-1 |
7 |
|
C. 0-7?787-04104-2 |
8 |
|
D. 0-41?40-56400-3 |
5 |
|
E. 0-875?7-79000-7 |
4 |
|
F. 0-4154?-33111-7 |
0 |
|
G. 0-51515-?2385-0 |
5 |
|
H. 0-41540-5?401-0 |
6 |
|
I. 0-30643-54?23-7 |
3 |
|
J. 0-21200-665?2-6 |
2 |
|
K. 0-71641-8000?-5 |
4 |
|
L. 0-41540-3351?-6 |
4 |
|
B. 0-?0735-00458-1
0x3+N+0x3+7+3x3+5+0x3+0+4x3+5+8x3+1=0
N+7+9+5+12+5+24+1=0
63+N=0
3+N=0
N=0-3=7
The missing digit is 7
C. 0-7?787-04104-2
0x3+7+Nx3+7+8x3+7+0x3+4+1x3+0+4x3+2=0
7+Nx3+7+24+7+4+3+12+2=0
66+Nx3=0
6+Nx3=0
Nx3=0-6
Nx3=4
We need Nx3=4, 14 or 24
8x3=24
N=8
E. 0-875?7-79000-7
0x3+8+7x3+5+Nx3+7+7x3+9+0x3+0+0x3+7=0
8+21+5+Nx3+7+21+9+7=0
78+Nx3=0
8+Nx3=0
Nx3=0-8=2
We need Nx3=2, 12 or 22
4x3=12
N=4
2. (this question will be on the quiz). What are check digits good for? Why do they bother to put check digits on UPC codes and things like that?