deletions | additions       diff --git a/bits1.tex b/bits1.tex  index 714ce5c..2b76984 100644  --- a/bits1.tex  +++ b/bits1.tex 
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We can sum $2,3$ and $4$ in $\ZZ$ and it happens that  $$(2+3)+4=5+4=9=2+7=2+(3+4),$$  so we can write also $9=2+3+4$, omitting the parentheses. Clearly, this Actually, tis  holds in general, considering for any  threearbitrary  numbers in $\ZZ$. \\  The same property also holds for the sum of bits. For example  $$ (1+0)+1=1+1=0=1+(0+1)=1+0+1.$$