Question

find the sum of all possible 4 digits numbers formed from 1, 3, 5, 2 where no digits are repeated.

Answer 1

it need some logical thinking ,

ones digit number will come by adding 1 3 5 2 , 6 times each giving 66, where 6 is at ones place and another 6 is carried to tens place

similarly for tens place 1 3 5 2 , will add 6 times each adding 6 from carry giving 72 where 2 comes at tens place and 7 is carried to hundreds place.

similarly for hundreds place 1352 , add 6 times each giving 66 adding 7 from carry giving 73 , where 3 comes at hundreds place and 7 carried to thousand place,

for thousand place 1235 add up 6 times each giving 66 adding 7 from carry giving 73 ,

so final answer = 73 3 2 6 = 73326