Remember that [tex] 40 = 2\cdot 2\cdot 10 [/tex].
So, dividing by 40 means dividing by 10, then by 2, then by 2 again.
So, we can go like this: let's divide by 10 first
[tex] 13 \div 10 = 1.3 [/tex]
Then, we divide by 2:
[tex] 1.3 \div 2 = 0.65 [/tex]
And by 2 again:
[tex] 0.65 \div 2 = 0.325 [/tex]
So, the decimal expansion ends after 3 digits.
