The clock calculator works like our usual clock. If it is 9 o'clock on the clock face, the clock will point to 1 o'clock after adding 4 hours. The output of Gauss's clock calculator is 1 instead of 13. If he wants to perform a more complicated operation, say, 7×7, then the clock calculator will give the remainder obtained by dividing 49=7×7 by 12, and the result is still 1.

When Gauss intends to calculate 7×7×7, the power of this calculator begins to stand out. This time, you don't need to multiply 49 by 7, but multiply the last result (that is, 1) by 7, and you can get the result 7. Therefore, you don't need to calculate how much 7×7×7 is equal to (exactly 343), you can know what the remainder is after dividing this number by 12 with a little calculation. Although Gauss didn't know what 7 99 was, the calculator told him that the remainder after dividing this number by 12 was 7.

This method can also be extended to any number. For example, if you enter 11 on a clock face with only 4 scales, you can get 3, because the remainder of 4 at 11 is 3. Even today, Gauss's clock calculator is still the core of Internet security, but the scales of these clocks are more than the number of atoms in hubble volume.