If 9th of the month falls on the day preceding Sunday, then on what day will 1st of the month fall?
Given N = 10p78pq is exactly divisible by 120.
Since the last digit of the dividend is 0, the last digit of N also should be 0.
Then obviously, q = 0.
i.e., N = 10p78p0
Now we have to find p.
We know 120 = 3 x 5 x 8 and 3, 5 and 8 are co-primes.
If N is divisible by 120 then it is divisible by 3, 5 and 8.
We know that, "If a number is divisible by 3 then the sum of its digits also divisible by 3"
Then, 1+ 0 + p + 7 + 8 + p + 0 = 16 + 2p
i.e., 16 + 2p must be divisible by 3
Then the possible values of p are 1,4,7,10,13 and so on
Since p is a digit, the possible values are 1, 4, 7
Now, N must be divisible by 8 also.
We know that, "If a number is divisible by 8 then its last 3 digits also divisible by 8"
Here 8p0 is a multiple of 8.
Now put all the above possible values of p then we have 8p0 = 810 or 840 or 870
From these, 840 is a multiple of 8.
Then the value of p = 4 and N = 1047840
Hence, the required sum = 1 + 0 + 4 + 7 + 8 + 4 + 0 = 24.