1we know, 5! = 120.
so any factorial after 5! will have 0 as its unit digit.
so we are only concerned with unit digit of 1!+2!+3!+4!= 1+2+6+24 = 33
so all of them a8,a9,.....,a16 will have unit's digit = 3
so summation of all = 9X3 = 27. [ans]
If an is the digit in the unit place of the number 1!+2!+3!+........+n! , then
a8 + a9 + a10 + ......... + a16 is equal to what ?______
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9 Answers
1
62it has to be noted here that each of the a8 and so on will have the same last digiit
So the answer will be last digit of a8*9
=last digit of 1!+2!+3!+4! + multiple of 10
= 1+2+6+24=33
Final answer will be last digit of 9.3 = 7
1why final anwer wll be last digit of 9.3....... i.e. 7... the answer should be 27 na??
62no we have to find the last digit surbhi..
What is the last digit of 9.9.9? isnt it the last digit of 81.9 = last digit of 9?
The last digit or any digit is always less than 10... so 27 does not make sense in any case.. does it?
62oops.. sorry for confusing every one ... i did not see the last digit..
I was taking the last digit of the sum
and the quesiton was the sum of the last digit :)
11i too think 27 wud be the ans
because it is a8 +..
not the last digit of a8+...
