The last day of the year, i.e., December 12, 23 we can write as 31.12.2023 or 31.12.23. If it is written in American style, i.e., 12.31.23, it gives interesting numbers, i.e., 123123. This work brings some interesting mathematical aspects of the number 123123. See the link of the work:

Inder J. Taneja, Mathematical Representations of the Last Day of the Year 23 Written American Style: 12.31.23 (123123), **Zenodo**, December 19, 2023, pp. 1-13, https://doi.org/10.5281/zenodo.10405771.

Whole work can be downloaded from the above link. Below are itens aborded in this work. These itens are for the representations of the number 123123 are given in frames.

- Crazy Representations
- Single Digit Representations and Patterns
- Single Letter Representations and Patterns
- Fixed Digits Repetitions Prime Patterns
- Prime Factors and Permutable Bases and Powers
- Embedded Palindromic Prime Patterns
- Pythagorean Triples and Patterns
- Upside-Down, Mirror Looking and Colors Patterns
- Magic Squares

### 1. Crazy Representations

### 2. Single Digit Representations and Patterns

### 3. Single Letter Representations and Patterns

### 4. Fixed Digits Repetitions Prime Patterns

### 5. Prime Factors and Permutable Bases and Powers

### 6. Embedded Palindromic Prime Patterns

### 7. Pythagorean Triples and Patterns

### 8. Upside-Down, Mirror Looking and Colors Patterns

### 9. Magic Squares

### References

**Inder J. Taneja**, 2019 In Numbers,**Zenodo**, December 31, 2019, pp. 1-27, http://doi.org/10.5281/zenodo.2529103.**Inder J. Taneja**, 2020 In Numbers: Mathematical Style,**Zenodo**, December 31, 2019, pp. 1-37, http://doi.org/10.5281/zenodo.3596193.**Inder J. Taneja**, 21 Mathematical Highlights for 2021,**Zenodo**, December 26, 2020, pp. 1-75, http://doi.org/10.5281/zenodo.4394408.**Inder J. Taneja**, Geometrical, Numerical, and Symmetrical Representations for the Days of 2020,**Zenodo**, October 04, 2020, pp. 1-201, http://doi.org/10.5281/zenodo.4065069.

Also see the link: Inder J. Taneja, Geometrical, Numerical, and Symmetrical Representations for the Days of 2020, https://inderjtaneja.wordpress.com/2020/10/07/geometrical-numerical-and-symmetrical-representations-for-the-days-of-2020.**Inder J. Taneja**, Hardy-Ramanujan Number – 1729,**Zenodo**, December 22, 2021, pp. 1-106, https://doi.org/10.5281/zenodo.5799640.**Inder J. Taneja**, Mathematical Beauty of 2022,**Zenodo**, December 26, 2021, pp. 1-78, https://doi.org/10.5281/zenodo.5805264.**Inder J. Taneja**, 23 and 2023 in Numbers and Patterns,**Zenodo**, December 22, 2022, pp. 1-51, https://doi.org/10.5281/zenodo.7473340.**Inder J. Taneja**, Fractional and Decimal Type Bordered Magic Squares with Magic Sum 2020,**Zenodo**, January 20, 2020, pp.1-25. http://doi.org/10.5281/zenodo.3613698.**Inder J. Taneja**, Block-Wise and Block-Bordered Magic and Bimagic Squares with Magic Sums 21, 21^2 and 2021,**Zenodo**, December 16, 2020, pp. 1-118, http://doi.org/10.5281/zenodo.4380343.**Inder J. Taneja**, Fractional and Decimal Type Bordered Magic Squares with Magic Sum 2021,**Zenodo**, December 16, 2020, pp. 1-33, http://doi.org/10.5281/zenodo.4327333.**Inder J. Taneja**, Block-Wise and Block-Bordered Magic Squares with Magic Sum 2022,**Zenodo**, December 28, 2021, pp. 1-38, https://doi.org/10.5281/zenodo.5807789.**Inder J. Taneja**, Mathematical Representations of the Last Day of the Year 23 Written American Style: 12.31.23 (123123),**Zenodo**, December 19, 2023, pp. 1-13, https://doi.org/10.5281/zenodo.10405771.**Inder J. Taneja**, Mathematical Aspects of 24 and 2024,**Zenodo**, December 19, 2023, pp. 1-40, https://doi.org/10.5281/zenodo.10406530.