diff --git a/day_01/program.py b/day_01/program.py
index 1448d88..e28bb68 100755
--- a/day_01/program.py
+++ b/day_01/program.py
@@ -2,7 +2,17 @@
 
 # https://adventofcode.com/2023/day/1
 
-import re
+NUMBER_DICT = {
+    "one": "on1e",
+    "two": "tw2o",
+    "three": "thr3ee",
+    "four": "fo4ur",
+    "five": "fi5ve",
+    "six": "si6x",
+    "seven": "sev7en",
+    "eight": "ei8ght",
+    "nine": "ni9ne",
+}
 
 
 def get_lines(filename: str) -> list:
@@ -26,13 +36,28 @@ def get_cal_val(line: str) -> int:
     return int(first + last)
 
 
-def main():
-    # lines = get_lines("test-input.txt")
-    lines = get_lines("input.txt")
+def replace_digit_strings(line: str) -> str:
+    for digit in NUMBER_DICT.keys():
+        line = line.replace(digit, NUMBER_DICT[digit])
+    return line
+
+
+def get_sum_cal_val(lines: list, spelled_out: bool) -> int:
     sum_cal_val = 0
     for line in lines:
-        sum_cal_val += get_cal_val(line)
-    print(f"Part 1: The sum of all calibration values is {sum_cal_val}.")
+        if spelled_out:
+            sum_cal_val += get_cal_val(replace_digit_strings(line))
+        else:
+            sum_cal_val += get_cal_val(line)
+    return sum_cal_val
+
+
+def main():
+    lines = get_lines("input.txt")
+    sum_cal_val = get_sum_cal_val(lines, False)
+    print(f"Part 1: The sum of all calibration values is: {sum_cal_val}")
+    sum_cal_val = get_sum_cal_val(lines, True)
+    print(f"Part 2: The sum of all calibration values is: {sum_cal_val}")
 
 
 if __name__ == '__main__':
diff --git a/day_01/test-input.txt b/day_01/test-input1.txt
similarity index 100%
rename from day_01/test-input.txt
rename to day_01/test-input1.txt
diff --git a/day_01/test-input2.txt b/day_01/test-input2.txt
new file mode 100644
index 0000000..41aa89c
--- /dev/null
+++ b/day_01/test-input2.txt
@@ -0,0 +1,7 @@
+two1nine
+eightwothree
+abcone2threexyz
+xtwone3four
+4nineeightseven2
+zoneight234
+7pqrstsixteen
diff --git a/day_01/test-input3.txt b/day_01/test-input3.txt
new file mode 100644
index 0000000..0cfbf08
--- /dev/null
+++ b/day_01/test-input3.txt
@@ -0,0 +1 @@
+2
diff --git a/day_01/test_program.py b/day_01/test_program.py
index ac7ecb3..893c3b0 100755
--- a/day_01/test_program.py
+++ b/day_01/test_program.py
@@ -14,6 +14,26 @@ class TestThing(unittest.TestCase):
         self.assertEqual(program.get_cal_val("3a2c3er"), 33)
         self.assertEqual(program.get_cal_val("1234567"), 17)
         self.assertEqual(program.get_cal_val("asdw3wemr"), 33)
+        self.assertEqual(program.get_cal_val("th95"), 95)
+        self.assertEqual(program.get_cal_val("g2"), 22)
+        self.assertEqual(program.get_cal_val("2"), 22)
+
+    def testReplaceDigitStrings(self):
+        self.assertEqual(program.replace_digit_strings("one"), "on1e")
+        self.assertEqual(program.replace_digit_strings("twosdftwo"), "tw2osdftw2o")
+        self.assertEqual(program.replace_digit_strings("zeightwosixa"), "zei8ghtw2osi6xa")
+        self.assertEqual(program.replace_digit_strings("4three2ffivee"), "4thr3ee2ffi5vee")
+        self.assertEqual(program.replace_digit_strings("onetwo"), "on1etw2o")
+
+    def testSumCalValPart1(self):
+        lines = program.get_lines("test-input1.txt")
+        sum_cal_val = program.get_sum_cal_val(lines, False)
+        self.assertEqual(sum_cal_val, 142)
+
+    def testSumCalValPart2(self):
+        lines = program.get_lines("test-input2.txt")
+        sum_cal_val = program.get_sum_cal_val(lines, True)
+        self.assertEqual(sum_cal_val, 281)
 
 
 if __name__ == '__main__':