# Easter

Catholic Easter | 9 April 2023 |

Orthodox Easter | 16 april 2023 |

### Algorithm for calculating the date of Orthodox Easter

**Y**-year.

**a**=**Y**%4;

**b**=**Y**%7;

**c**=**Y**%19;

**d**=(19***c**+15)%30;

**e**=(2***a**+4***b**-**d**+34)%7;

**f**=3+(**d**+**e**+21)/31;

**g**=(**d**+**e**+21)%31;

month=f;

day=g+1;

### Algorithm for calculating the date of Catholic Easter

**Y**-year.

**G**=[**Y**%19]+1 (G - gold number in the metonic cycle);

**C**=[**Y**/100]+1 (if Y is not a multiple of 100, then C is the century number);

**X**=[3·**C**/4]-12] (correction for the fact that three of the four year-folds are not 100 leagues;

**Z**=[(8·**C**+5)/25]-5] (synchronization with the lunar orbit, year is not a multiple of the lunar month);

**D**=[5·**Y**/4]-**X**-10 (in March, the day? D mod 7 will be Sunday);

**E**=[(11·**G**+20+**Z**-**X**)%30] (ground or epact - indicates the day of the full moon);

If (**E**=24) or (**E**=25 AND **G**>11) then increase E by 1;

**N**=44-**E** (N March is the day of the calendar full moon);

If **N** < 21 then increase N by 30;

**N**=**N**+7-[(**D**+**N**)%7];

If **N** > 31 then the date of Easter (**N**-31) April is otherwise the Easter date of March N.