Question

Thanks in advance.
I have a string:

A = 'asdfghjklmn'

How can I get a substring having a maximum length which is a multiple of three?

Answer 1

You can use slice notation and integer arithmetic.

>>> a = 'asdfghjklmn'
>>> a[:len(a)//3*3]
'asdfghjkl'   
>>> len(a)
11
>>> len(a[:len(a)//3*3])
9

In general, n//k*k will yield the largest multiple of k less than or equal to n.