How many zeroes are there in 2007!?

1. Till 2007 we have 2000/1000 = 2 of 10^3 --- gives 6 zeroes 2. Till 2007 we have 2000/100 = 20 of 10^2 which includes above 2 so additional 18 --- gives 36 zeroes 3. Till 2007 we have 2000/10 = 200 of 10 which includes above 20 so additional 180 -- gives 180 zeroes 4. Till 2007 we have 1003 even numbers so = 1003 multiples of 2s – These are enough to form multiples of 5s below 5. Till 2007 we have 2000/125 = 8 of 5^3 --- multiply with 8 of 2^3 --- gives 8x3 = 24 zeroes 6. Till 2007 we have 2000/25 = 40 multiples of 5^2 which includes above 8 so additional = 32 of 5^2 --- multiply with 32 of 2^2 --- gives 32x2 = 64 zeroes 7. Till 2007 we have 2005/5 = 401 multiples of 5 which includes above 40 so additional = 361 of 5 ---- multiply with 401 of 2 --- gives 401 zeroes. 8. SO we will have 6+36+180+24+64+401 = 711 zeroes in 2007! read less