Hi
I am Prakash and am I here with my First magic maths tutorial .
We will calculate the number of a digit in a given factorial number.
like- number of 2's in 20! or number of 3's in 20!
so lets start
this is a very simple technique you just need to divide the number recursively or continuosly till we get 1 and then simply add all of them .
we are providing a picture for that
for 2 we are adding 10+5+2+1=18
for 3 we are adding 6+2
your task to find for 5
now let us see what if we are doing it for 10
clearly we can take 5*2 as 10.
now find the number of 2's and 5's in the number and then whichever is lower just that number of 10's will be available .
like we get 5 2's and 6 5's so only five times we can multiply 2 with 5 . so 5 number of 10's will be available .
have question ? use our comments box .
I am Prakash and am I here with my First magic maths tutorial .
We will calculate the number of a digit in a given factorial number.
like- number of 2's in 20! or number of 3's in 20!
so lets start
this is a very simple technique you just need to divide the number recursively or continuosly till we get 1 and then simply add all of them .
we are providing a picture for that
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| picture for magic maths 1 |
for 3 we are adding 6+2
your task to find for 5
now let us see what if we are doing it for 10
clearly we can take 5*2 as 10.
now find the number of 2's and 5's in the number and then whichever is lower just that number of 10's will be available .
like we get 5 2's and 6 5's so only five times we can multiply 2 with 5 . so 5 number of 10's will be available .
have question ? use our comments box .
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