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Number System (Factorial - 4) (in Hindi)
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Number System (Factorial - 4) (in Hindi)

Bharat Gupta is teaching live on Unacademy Plus

Bharat Gupta
Engineer by degree Mathematician by Heart. Having 22 years of teaching experience. More than 20000 students selected.

Comments
(5)
U
Unacademy user
sir kon se month ki h yeh nhi pata chalta or April ki kaha update h
AC
Sir in the last question you have given the sum upto factorial 100... but during solution why have u solved until factorial 4
Pg
Prateek gupta
a year ago
5 factorial se sabke unit digit zero hota hai (5! = 5×4×3×2×1 =120) to koi matlb nhi lene ka
Pg
Prateek gupta
a year ago
5 factorial se sabke unit digit zero hota hai (5! = 5×4×3×2×1 =120) to koi matlb nhi lene ka
AC
My apologies.. I have understood the logic.. U are right sir
in the last question the unit digit of the power is 1. And when I used to solve it it comes out to be 1^1+2^1+3^1+4^1 =10, for which unit digit is 0. while in the solution given by sir, unit digit comes out to be something else. please help me out with this.
Rohan kumar
6 months ago
1!=1,2!=2,3!=6,4!=24...so their unit digit sum is 13..unit digit = 3
sir' solution is 1^1+2^1+6^1+4^1 which is 13 and UD is 3.. where does this 6 instead of 3 is there.. this is my doubt.
AM
trailing num ni smjh aaiya phr bta dijiye