Empirical test on strings

[Emieno]

A DNA string is long but I wonder how long it is? I mean those you might have used in different experiments, and that they are many in number. How many strings (N) are usually used in an experiment ?

I am sorry, I am not a biologist, never "played" with any bilogcal experiment before.

for example, string_i = ATCGATAGCTTGAATGA --> length=17, like character counting, i runs from 1 to N.

Thanks a lot for your information