Number of odd days in (1600 + 300) years = (0 + 1) = 1.

78 years = (19 leap years + 59 ordinary years)

        = (38 + 59) odd days = 97 odd days = 6 odd days.

    12 days of January have 5 odd days.

:. Total number of odd days = (1 + 6 + 5) = 5 odd days.

:. The desired day was 'Friday'.

1600 years have 0 odd day.

300 years have 1 odd day.

94 years = (23 leap years + 71 ordinary years)

= (46 + 71) odd days = 117 odd days = 5 odd days.

Number of days from 1st Jan, 1995 to 25 th Dec, 1995 = 359 days.

 = (51 weeks + 2 days) = 2 odd days.

:. Total number of odd days = (0 + 1 + 5 + 2) odd days = 1 odd day.

:. Required day is 'Monday'.

Find the day on 1st October, 1994.

1600 years contain 0 odd day.

300 years contain 1 odd day.

93 years = (23 leap years + 70 ordinary years) 

= (46 + 70) odd years = 116 odd days = 4 odd days.

Days from 1st Jan, 1994 to 1st Oct, 1994

Jan    Feb    March     April    May     June    July    Aug    Sept        Oct

31 +   28  +   31    +   30  +  31  +  30   +  31  +  31  +  30   +    1

= 274  days = 39 weeks + 1 days = 1 odd day.

:. Total number of odd days = (0 + 1 + 4 + 1) = 6.

:.  1st Oct, 1994 was 'Saturday'

:. Monday fell on 3rd October, 1994.

During October 1994, Monday fell on 3rd, 17th and 24 th.

In order that the calendar for 1995 and 2006 be the same, 

1st January of both the years must be on the same days week.

For this, the total number of odd days between 3 1st Dec, 1994 

and 31 st Dec, 2005  must be zero.

We know that an ordinary year has 1 odd day and a leap year has 2 odd days. 

During this period there are 3 leap years, namely  1996 , 2000 and 2004 and 8 

ordinary years. 

:. Total number of odd days during this period (6 + 8) + 14 = 0

i.e. 0 odd day.

Hence, the calendar for 1995 will serve for 2006.

In order to prove the required result, we have to show that the number of odd days between last day of February and last day of October is Zero.

Number of days between these dates are.

March    April     May     June   July     Aug     Sep     Oct

31      +   30   +   31  +  30  +  31  + 31  +   30   +   31

`= 241 days = 35 weeks 

:. Number of odd days during this period = 0.

Hence, the result follows.