Which of the following day could be the 18 th October 2050?

From Zeller's Formula f = k + [13 x m - 1 / 5] + D + [D/4] + [C/4] - 2 x C. In this case k = 18 (since 18^th October) Month m = 8 (As march = 1, April = 2, May = 3, October = 8) D is the last two digit of year here D = 50 (As year is 2050) C is the 1^st two digit of century here C = 20 (As year is 1950) f = 18 + [13 x 8 - 1 / 5] + 50 + [50/4] + [20/4] - 2 x 20. f = 18 + [103/5] + 50 + [12.5] + [5] - 40. f = 18 + 20 + 50 + 12 + 5 - 40 = 65. When divided by 7 we will get remainder 2, hence number of odd days is 2, So 18^th October 2050 is 2 days more than Sunday, i.e Tuesday.