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+See: https://adventofcode.com/2023/day/1
+** Part 1
+*** Purpose
+Given a list of lines of characters, each with a minimum of one integers:
+
+#+begin_example
+1abc2
+pqr3stu8vwx
+a1b2c3d4e5f
+treb7uchet
+#+end_example
+
+Reduce each line to the first and last integer, then add all lines together. If a line contains a single integer, count that integer twice.
+
+*** Method
+
+The solution to this is obvious---filter the non-numeric characters out of the each line, index the first and last characters, and then make the summation.
+
+** Part 2
+*** Purpose
+The next part now asserts that some spelt out numbers are unaccounted for. For example:
+
+#+begin_example
+two1nine
+#+end_example
+
+Should return the digit "29". We must calculate the new sum, with this rule in place.
+
+*** Method
+With this addition, it makes the most sense to perform some cleaning on each input string---substitute spelt numbers for actual numbers, then send it down the usual processing.
+
+Lots of code was required to make this work---also noteworthy, is that this useful piece of information is not in the instructions:
+
+#+begin_example
+twone -> 21
+#+end_example
+
+because a letter is shared.