Questions
The sum of all numbers greater than 1000 formed by using the digits 0, 1, 2, 3, no digit being repeated in any number, is
detailed solution
Correct option is A
All the numbers are of four digits and they do not have 0 in thousand’s place.The number of numbers having 0 in unit’s place = 3! (∵ the other three places are to be filled by 1, 2 or 3).The number of numbers having 1 in unit’s place =2P1×2P2(∵ thousand’s place can be filled by one of 2, 3 and the remaining two places can be filled by the remaining two digits).Similarly, the number of numbers having 2 or 3 in unit’s place=2P1×2P2 in each case.Thus, the sum of the digits in unit’s place for all the numbers=3!×0+2P1×2P2×1+2P1×2P2×2+2P1×2P2×3=4+8+12=24Similarly, the sum of the digits in ten’s and hundred’s places = 24 each.Now, the thousand’s place can have only 1 or 2 or 3.Number of numbers having 1 in thousand’s place = 3!, (for the other three places will be filled by 0, 2, 3).Similarly, the number of numbers having 2 or 3 in thousands’s place is 3! in each case.∴ Sum of the digits in the thousands’s place for all the numbers = 3! × 1 + 3! × 2 + 3! × 3 = 6 + 12 + 18 = 36.∴ Required sum of all the numbers= 36 × 1000 + 24 × 100 + 24 × 10 + 24 × 1= 36000 + 2400 + 240 + 24 = 38664.Similar Questions
The total number of 5-digit numbers of different digits in which the digit in the middle is the largest is
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