Modular arithmetic
（重定向自Congruence class）
![Time-keeping on this clock uses arithmetic modulo 12.](/Images/godic/202501/06/Clock_group.svg2043.png")
In mathematics, modular arithmetic is a system of arithmetic for integers, where numbers "wrap around" upon reaching a certain value—the modulus (plural moduli). The modern approach to modular arithmetic was developed by Carl Friedrich Gauss in his book Disquisitiones Arithmeticae, published in 1801.