Hi all, I was watching a tv show about an extraordinary man who calculates mentally the day of the week of any date. Then I wrote this program for the HP 35s that uses one of that algorithms.

DAY OF THE WEEK FOR HP 35s (FROM 1901 TO 2099)Table of Contents

=================

1 Using the program

2 Program listing

3 Registers

4 Revision1 Using the program

~~~~~~~~~~~~~~~~~~~~First execute the program: XEQ W ENTER.

Insert the day and press R/S.

Insert the month and press R/S.

Insert the year (from 1901 to 2099) and press R/S.Then it will show a number that corresponds to the

day of the week according to this table:Day Number

-----------+--------

Sunday 0

Monday 1

Tuesday 2

Wednesday 3

Thursday 4

Friday 5

Saturday 62 Program listing

~~~~~~~~~~~~~~~~~~Line Instruction

------+--------------------

W001 LBL W

W002 INPUT D

W003 INPUT M

W004 INPUT Y

W005 033614625035

W006 1E13

W007 10

W008 RCL M

W009 y^x

W010 ÷

W011 ÷

W012 FP

W013 10

W014 x

W015 IP

W016 STO N

W017 RCL Y

W018 4

W019 RMDR

W020 x!=0? ;(not equal)

W021 GTO W038

W022 RCL Y

W023 100

W024 RMDR

W025 x!=0? ;(not equal)

W026 GTO W032

W027 RCL Y

W028 400

W029 RMDR

W030 x!=0? ;(not equal)

W031 GTO W038

W032 RCL M

W033 3

W034 x>y?

W035 GTO W038

W036 1

W037 STO+ N

W038 RCL Y

W039 1

W040 -

W041 ENTER

W042 ENTER

W043 ENTER

W044 100

W045 INT÷

W046 1

W047 +

W048 4

W049 INT÷

W050 -3

W051 x

W052 x<>y

W053 4

W054 INT÷

W055 +

W056 +

W057 RCL N

W058 +

W059 RCL D

W060 +

W061 7

W062 RMDR

W063 STO W

W064 VIEW W

W065 RTN234 Bytes

3 Registers

~~~~~~~~~~~~Register Use Notes

----------+-----------------+----------------

D Day of month

M Month

Y Year

N Modulus Internal usage

W Day of the week

4 Revision

~~~~~~~~~~~06/23/10 - Initial release

*Edited: 23 June 2010, 5:29 p.m. after one or more responses were posted*