Stony Brook University
MAT 118 Spring 2013
Assignment 9 due in Recitation, week of April 8
A. Prime numbers
- Mindscape 8 page 81
- Mindscape 11 page 81
- Mindscape 14 page 81. (The Goldbach Conjecture
is stated on page 80).
- Mindscapes 23, 24, 25 page 82.
B. Clock arithmetic and check digits
- Find two barcodes and study the UPC numbers. Check
that the sum $3d_1+d_2+3d_3+d_4+3d_5+d_6+3d_7+d_8+3d_9+d_{10}+3d_{11}+d_{12}$
is always a multiple of $10$ ("equivalent to $0$ mod $10$"). Explain
carefully why any missing number can be restored if the other eleven
are known. Show for one of your barcodes how $d_2$ can be retrieved if
it is missing.
Same for $d_3$.
- Mindscapes 1, 2, 3, 4 page 92. "Reduce $7$ mod $3$" means
give the remainder when $7$ is divided by $3$. Equivalence is
discussed on page 88.
- Mindscapes 27, 28, 29 page 95.
Remember: Collaboration is fine, but
what you hand in should be your own work. Handing in
something you copied is plagiarism and will cost you if it is
detected. Write down what you tried and how it worked.