The task was to find out the pattern on the isbn Book codes. These books had to be published before 2007 because it had ten numerals besides 13 numerals that were published after 2007. The isbn codes went up to the digit X or 10.
We began this task by finding a few books and writing their code down. We took a code and used its ISBN code to calculate a number;
For instance one of Tolkein's books has an ISBN code on the back of
0−04−823208−4
Take this code and calculate this sum:
(1×0)+(2×0)+(3×4)+(4×8)+(5×2)+(6×3)+(7×2)+
+(8×0)+(9×8)+(10×4)
We calculated different isbn codes and came up with different numbers. We found out that all the answers are divisible by 11!!
Using this divisibility rule we found out how to solve the second part of the book Codes problem. This task was to find the ? mark in the isbn code that we were given. Which was;
0-74755?-19-1
Now we have learned how to figure out the question mark our solution was that we knew all answers to the isbn codes were divisible by 11. So then we worked backwards by dividing the answer by 11 going up in numbers. If it worked and it was divisible by 11 we knew it was right. The final answer was 8.
We found out it was very challenging and we used strategies such as:
Factors and multiples, Generalising, Trial and improvement, Investigations, Working systematically. Multiplication & division, Addition & subtraction, Calculators and Combinations.