How many zeros are in a femtosecond?

Answer 1

I could write 1 femtosecond as "1 femtosecond" : not a zero in sight.

or as 0.000001 nanoseconds (6 zeros)

or .000001 nanoseconds (5 zeros)

1 fs = 10-15 seconds so there are 14 0s between the decimal point and the 1.