Aptitude - Calendar - Discussion

8th Feb, 2005 Tuesday.

We need to calculate 8th Feb, 2004 rite.

NOTE:

We need to understand that years like 2004, 2008, 2000 having 2 odd day because these are divisible by 4. The year not divisible by 4 is having 1 odd day only (simply means 2004, 2008, 2000 having 29 days in feb so total 366 days) (2001, 2002, 2003 like which are not div by 4 having only 28 day in feb so tot 365 days).

If you confused about odd day means just divide the total number of days by 7.

366/7 = 2 remainder so two odd days.

365/7 = 1 remainder so one odd day.

GOT IT:).

So let me come to our problem.

8th Feb, 2005:

So total days is.

Jan = 31.

Feb = till 8 so 31+8=39 is there in 2005.

8th Feb, 2004:

So calculate from 2004 8th feb to 2005 8th feb (we already calculate 39 days in the 2005 till feb).

Now 2004 feb contains 29 days we just need to calculate from 8th only.

Feb 8th to feb 29 = 21 days.

March = 31.

Apr = 30.

May = 31.

.
.

Dec=31.

Already we calculate the 2005 before it contains total of 39 days.

So add all these.

39 (2005's tot days because till feb means jan 31 day+ feb 8 day) +21 (2004 feb because from 8 to 29 only need) +31 (mar 2004) +30 (apr 2004) +...+31 (dec) = 366.

Now 366/7 = 2 days remainder.

0 1 2 3 4 5 6.

S m t w t f s.

2005 feb 8 is Tuesday.

Now need 2004 feb 8. Here calculate from higher to lower year so just minus the reminder 366/7 = 2 from Tuesday.

SO SUNDAY.

We are supposed to know the weekday on 8th Feb. 2004.

To all those who have doubt.

2004 = 1600 + 400 + 2001, 2002, 2003, (31 + 8 days of feb. ).
So odd days for the 1600 year = 0 odd days.
Odd days for 400 year = 0 odd days.
2001, 2002, 2003 all three are an ordinary year so odd days will be =3*1= 3 odd days.
And in 2004 total time period will be of 39 days ----> means 39/7= 5 weeks + 4 odd days.
So total odd days will be = 3+4= 7 (means 0 odd days).
So we finally got 0 odd days which means Sunday.

Hope you got it.

Just memorie these tables:

Month code:
Jan -0
Feb- 3
March-3
April-6
May-1
June-4
July-6
Aug-2
Sep-5
Oct-0
Nov-3
Dec-5

Day code:

Sun-0,7
Mon-1
Tue-2
Wed-3
Thur-4
Fri-5
Sat-6

Year code:

1600-1699=6
1700-1799=4
1800-1899=2
1900-1999=0
2000-2999=6

By using the formula,

Formula = day code + month code + year code + (x-1900) + (x-1900)/4

Our qn is : 8th feb 2004.
=> 8+3+6+104+104/4.
=>8+3+6+104+26.
=>147.

Since there 7 days in a week so divide 147 by 7.
So, 147/7 =>0 remainder.

0=>sunday.

@All.

Month code:
Jan -0
Feb- 3
March-3
April-6
May-1
June-4
July-6
Aug-2
Sep-5
Oct-0
Nov-3
Dec-5

Day code:

Sun-0,7
Mon-1
Tue-2
Wed-3
Thur-4
Fri-5
Sat-6

Year code:

1600-1699=6
1700-1799=4
1800-1899=2
1900-1999=0
2000-2999=6

By using the formula,

Formula = Day code + Month code + Year code + (x-1900) + (x-1900)/4.

Our qn is : 8th Feb 2004.
=> 8+3+6+104+104/4.
=>8+3+6+104+26.
=>147.

Since there 7 days in a week divide 147 by 7.
So, 147/7 =>0 remainder.

0=>Sunday.

@Shekher Anand Mishra.

=> 20-04-1780.
=> 1600 = 0 odd days(because 1600 is leap year) .
=> 100 = 5 odd days(in 100).
=> 79 = in 79 (79/4 = 19(quotient)) so 19 is leap year:
=> And 70 is ordinary year.
=> 19*2 + 70*1 = 15 weeks + 3 odd days.
=> 31 +29+30+20 =120=> 120/7 = 1 odd days.
=> 0 +5 +3 + 1 =9 => 9/7 => so 2 is reminder= 2 odd days.
=> So answer is Tuesday.

0 = SUNDAY.
1 = MONDAY.
2 = TUESDAY.
3 = WEDNESDAY.
4 = THURSDAY.
5 = FRIDAY.
6 = SATURDAY.

We need to split that year of 2004.
=> 1600 + 400 + 3 + (Jan+8).
=> 0 + 0 + 3(1) + (3+8).(Here January Have 3 odd day then also we put 3 in there).
Substitute all the values.
3 + 3 + 8 = 14(day).
=>14/7 =2(weeks)
=>2 weeks + 0 odd day.
So, the Answer is SUNDAY.

In this question, we are assuming that 2005 is not a leap year and 2004 as a leap year; every non-year odd days gets incremented by 1 and leap year increments by 2 the same subtract the odd days if you calculate in reverse order.

Considering our case we are calculating from 2005 to 2004 and since 2004 is a leap year subtract 2 days (i.e) Tuesday - 2 = Sunday.

@Shekher Anand Mishra

You Need to remember this thing.
i.e
Year Code
1600-1699=6
1700-1799=4
1800-1899=2
1900-1999=0
2000-2099=6
2100-2199=4
2200-2299=2
2300-2399=0
.
.
.
.and so on...

Month Code
Jan-0
feb-3
Mar-3
Apr-6
May-1
June-4
July-6
Aug-2
Sep-5
Oct-0
Nov-3
Dec-5

Day Code
Sun-0
Mon 1
Tue 2
Wed 3
Thr 4
Fri 5
Sat 6

0 = SUNDAY.
1 = MONDAY.
2 = TUESDAY.
3 = WEDNESDAY.
4 = THURSDAY.
5 = FRIDAY.
6 = SATURDAY.

We need to split that year of 2004.
=> 1600 + 400 + 3 + (Jan+8).
=> 0 + 0 + 3(1) + (3+8). // (Here January Have 3 odd day then also we put 3 in there).
Substitute all the values.
3+3+8= 14 weeks + 0 odd day.
Answer is SUNDAY.

@Keyuri & @Harry.

If year is divided by 4 or 400. so it is called leap year.
If year is in century then must be divided by 400.

100/400 = 100 as a reminder
400/400 = 0 as a reminder, so leap year
800/400 = 0 as reminder.., so leap year
.
.
.
. like that

Understood...!!!!