Find the number of zeroes in 10 x 20 x 30x……x 1000.
A
100
B
124
C
130
D
154
Correct Answer: 124
Concept:Take 10 as common form each term.Number of trailing zeroes in n! = divide n by 5 and all the quotients till it reaches less than 5. Calculations:10 x 20 x 30 x …… x 1000= (10 x 1) x (10 x2) x (10 x 3) x ………………… x (10 x 1000)= 10100 x (1 x 2 x 3 x …………… x 100)= 10100 x 100!Number of zeroes = 100 + 100/5 + 100/52 = 100 + 20 + 4 = 124