Question

the number of consecutive zeros in 2^3*3^4*5^4*7

 

 

Answer 1

See, this question is pretty easy, as you can just multiply and find the answer.
But for questions such as 100! [It means all numbers from 1 to 100 multiplied] and they ask you the number of zeroes. So, to solve these questions faster, you must know that every zero in a number is due to multiplication of one 5 and one 2. like in 700, there are 2 pairs of 5*2 [=10]. in X= 5*3*3*9*4*5*6*25, we see that there are three 2s and four 5s. We take the minimum number of 2s and 5s [Logically and theoretically too]. So, the number of zeros in X will be 3. 
In your question, there are three 2s and four 5s. Since there are only three 2s, there will be only one three consecutive zeros.
Good if understood or comment below :-)

Answer 2

2^3*3^4*5^4*7 = 8*81*625*7
                     = 2835000

The no.of consecutive zeros = 3