ABSTRACT
Dan’s fi rst number was C = 18, so Tim needed to compute 1823 mod 55. This was not as easy as the calculations Dan had done because 1823 is too big for his calculator and had to be rounded. Luckily, however, Tim had already computed that 1823 mod 55 = 2 (see Chapter 17). Using repeated squaring and reducing as he went along, he computed the rest of the numbers:
823 mod 55 = 17 2923 mod 55 = 24 523 mod 55 = 15 2423 mod 55 = 19 923 mod 55 = 14.
