Find sum of all the number greater than 10000 formed by the digits 0,2,4,6,8 no digit being repeted?
Raj kumar , 7 Years ago
Grade 11
1 Answers
Arun
Last Activity: 7 Years ago
Dear Raj
1. Fix the units digit of the 5 digit number . say _ _ _ _ 2 2. The total of such numbers with 2 in the units place is 4! i,e 24 3. In the same manner there are 24 such numbers that end with 0,4,6 & 8 4. Now the sum of all the numbers in the Units place is 24 * (0+2+4+6+8) = 24 * 20 = 480 5. The same is true for the 10th place, 100th place, 1000th place & 10,000th place. Hence the sum of all the 5 digit numbers using 0,2,4,6,8 is 480 (1+10+100+1000+10000) = 480 (11111) = 5333280-----------------------------(A) 6. Following the same approach as mentioned in steps 1 to 5, the sum of all the 4 digit numbers (5 digit numbers starting with 0 ) is = 6*(2+4+6+8)* (1+10+100+1000) = 6* 20 * 1111 = 133320--------------------------------(B)
7. Hence the sum of all the 5 digit numbers using 0,2,4,6,8 > 10000 = (A) - (B) = 5333280 - 133320
= 5199960
Regards
Arun(askIITians forum expert)
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