Question

how zero in 49 fectorial?

Answer 1

49!

how can we get zero in the unit place??

or when can we get 0 in the unit place??

Ans : Only when we have 10 or a multiple of 10

So, by finding the number of 10 in 49! we can find the number of zeroes in 49!

10 = 5 * 2

To make it more simple we can find the combinations of 5 * 2 to get 10 and the number of zeroes .

As we know just by looking that there are greater number of 2's than 5 so we can just count total 5 in 49!

5 = One 5                                  

10 = One 5

15 = One 5                                                  (Eg : 3 * 5)

20 = One 5

25 = Two 5                                                   (As 5 * 5)

30 = One 5

35 = One 5

40 = One 5

45 = One 5

Total 5 = Ten 5

So the number of zeroes in 49! will be 10