Divisible by this year??? v2015 (Part 2: A Jinx from the past!!!)

Find the minimum value of n n where n n is an integer such that the number of trailing zeroes of ( n + 2 ) ! × ( n + 0 ) ! × ( n + 1 ) ! × ( n + 4 ) ! (n+2)! \times (n + 0)! \times (n + 1)! \times (n + 4)! is divisible by 2015 2015

( 201500000 201500000 has 5 5 trailing zeroes while 2000015000 2000015000 has 3 3 )

You may like Divisible by this year? v2015 (Part 1: Happy New Year!)

2015 None of the above 2025 2024

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

1 solution

Rindell Mabunga
Jan 3, 2015

Let f ( n ) = ( n + 2 ) ! × ( n + 0 ) ! × ( n + 1 ) ! × ( n + 4 ) ! f(n) = (n+2)! \times (n + 0)! \times (n + 1)! \times (n + 4)!

The domain of this function is [ 0 , + ) [0, + \infty )

So let's first check f ( 0 ) f(0) .

( n + 2 ) ! × ( n + 0 ) ! × ( n + 1 ) ! × ( n + 4 ) ! (n+2)! \times (n + 0)! \times (n + 1)! \times (n + 4)! = ( 0 + 2 ) ! × ( 0 + 0 ) ! × ( 0 + 1 ) ! × ( 0 + 4 ) ! = (0+2)! \times (0 + 0)! \times (0 + 1)! \times (0 + 4)! = 2 ! × 0 ! × 1 ! × 4 ! = 2! \times 0! \times 1! \times 4! = 48 = 48

There are 0 0 trailing zeroes in 48 48 . And since 0 0 is divisible by 2015 2015 , the answer is 0

Same trick applied

U Z - 6 years, 5 months ago

Hahaha! I knew there was something tricky like this. Good question!

Jake Lai - 6 years, 5 months ago

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...