math destroyer Q

[themrn]

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The value of 50! is the product of the first fifty positive integers. Find the maximum number of times that 10 will divide this number (that is, find the number of trailing zeroes in the value of 50!)

??? i read the explanation but have no idea what it's talking about..

the answer is 12

 

[denttal]

Just found this on the internet:

Each multiple of 5 - taken together with some even number - contributes a multiple of 10. Each multiple of 25, however - taken together with some even number - contributes two multiples of 10. So we can count the number of multiples of 5 in 50!. Then we can add another count of the number of multiples of 25 in 50!. There are 2 multiples of 25 in 50! (25 and 50) and 10 multiples of 5 (5, 10, 15, 20, 25, 30, 35, 40, 45, 50). 2+10 = 12. Thus, there are a total of 12 zeros in 50!

 

[themrn]

Just found this on the internet:

Each multiple of 5 - taken together with some even number - contributes a multiple of 10. Each multiple of 25, however - taken together with some even number - contributes two multiples of 10. So we can count the number of multiples of 5 in 50!. Then we can add another count of the number of multiples of 25 in 50!. There are 2 multiples of 25 in 50! (25 and 50) and 10 multiples of 5 (5, 10, 15, 20, 25, 30, 35, 40, 45, 50). 2+10 = 12. Thus, there are a total of 12 zeros in 50!

thanks!!! got it!!

just wondering if real DAT would be worded like this..... so confusing 🙁

 

[denttal]

from what I have heard, the math section is more simple than Math Destroyer. I looked at the other question you posted as well, and I have no idea how to solve that one... I don't think that they will be this difficult!

DAT Bootcamp suggested a strategy for approaching this section. They said if you come across any difficult/time consuming problems just make a guess and mark the problem. Then continue through the section, completing/answering all of the problems you can quickly do. Once you get through all of the questions, you can go back and work on your marked questions. When you go through your marked questions you can even still skip the MOST difficult ones, so that when time runs out you will have completed the most problems w/ the best chance of getting them correct 🙂