775 B
775 B
OhThatsA 
An app to help you learn how to calculate day of the week from any date.
App
Mostly made to try out Dart/Flutter.
Method
The day of the week can be calculated by:
(day value + month value + year value + century value + leap year value) % 7
Every one of these value comes from a set of constants or is calculable from the date.
This app helps you practice memorizing and calculating these values.