Question

find the sum of all the numbers which is having units place 1 (between 10 and 1000)​

Answer 1

Answer:

Step-by-step explanation:

How do you find the sum of digits in the unit place, of all numbers formed with the help of 3,4,5,6 taken all at a time?

so if we make numbers using only 3,4,5,6… ( considering there are 4 digits in the number).. so  4!=24  numbers can be made

And consider no repetition of numbers in a digit.. then the units place can be filled up in only 4 ways that is : 3,4,5 and 6.

So total number of repetitions of of the set  3,4,5,6  is  244=6  

so the total sum will be :  6×18=108  

Hope I am right !