Pre requisites:

365 days 52weeks + 1 odd day

366 days 52weeks + 2 odd days

mon code: 0

sun code: 1

tue code: 2

wed code: 3

thu code: 4

fri code: 5

sat code: 6

28 days in month     code: 0

29 days in month    code: 1

30  days in month   code: 2

31  days in month   code: 3

400 years    code: 0

200 years    code: 3

100 years    code: 5

300 years    code: 1

100th year example:

24leap years + 76 normal years

24*2(as 2 odd days in leap year i.e. 366 days 52weeks + 2 odd days)+ 76*1(as only odd day in normal year i.e. 365 days 52weeks + 1 odd day)

hence,

24*2 + 76*1

48+76

124

1. 15th aug 1947

1946 + JAN + FEB + MAR + APR + MAY + JUN + JUL + 15

             3+0+3+2+3+2+3+15 = 31

1946

1600+300+46

0+1+57=58

58+31=89

46

11+35

11*2+35*1

22+35= 57

11 FEB 2002

2001+ JAN + 11

           3+11=14+1 = 15 =15/7= 1 MONDAY

2000 + 1

0 + 0LP+1NLP

0+0+1=1

03 NOV 1975

1974 + J+F+M+A+M+J+J+A+S+O+3

             3+0+3+2+3+2+3+3+2+3+3= 27

1600+300+74

0+1+ 18LP+56NP

1+18*2+56*1

37+56

Find the day for the date 26/07/1987 and post your answer in the comments