All answers that can be accumulated from the instructions given share the fact that they are in the nine times tables. Every number in the nine times table (with the exception of ninety and ninety-nine) has the same symbol. The reason that ninety and ninety-nine do not have the symbol that corresponds to the rest of the nine times table is that unless the numbers given went up into three digits it is impossible to achieve these numbers using the instructions given.
The reason that the answer is always in the nine times tables is:
99 9 + 9 = 18 99 – 18 = 81
So…
a = a positive whole number in the nine times table.
Therefore…
a – a = a.
What if my start number is not a multiple of 9, but one less than a multiple of 9?
98 9 + 8 = 17 98 – 17 = 81
So…
B = 1 less than a positive whole number that is in the nine times table.
Therefore…
b – b = a.
What if my start number is two less than a multiple of 9?
97 9 + 7 =16 97 – 16 = 81
So…..
C=2 less than a positive whole number in the nine times table
Therefore…
c – c = a
Most numbers (with the exception of ninety and ninety-nine) that can be represented by a have the same symbol.