This is really simple. You enter a month, day and year. Then you press the Day of the Week button and out pops a number from 0 to 6.

0 is Sunday, 1 is Monday, and so on.

It claims to work for any date after September 14, 1752. I’ve tried it with 2017 and it seems to work fine.

You can see the program listing here:
std01-day-of-week.65.txt

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