I came across this notation in the CAA module 0 sample questions. See photo:

enter image description here

It looks like it means lower bound but not sure. Can’t find any info. on google either. Anyone come across this notation before in this context? If so, what does it mean?

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    $\begingroup$ This look like the floor function typically denoted by $\lfloor x\rfloor$ (but can also be denoted by $[x]$) which provides the greatest integer less than or equal to $x$. $\endgroup$ Jun 17, 2020 at 18:33
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    $\begingroup$ $x=[x]+\{x\}$ where $[x]$ is the integer part of $x$ and $\{x\}$ is the fractional part of $x$, e.g. 3.14 = 3 + 0.14. $\endgroup$
    – pshmath0
    Jun 17, 2020 at 18:34
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    $\begingroup$ Does this answer your question? what does this symbol mean: [] but without the top bars? $\endgroup$
    – Martin R
    Jun 17, 2020 at 18:38
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    $\begingroup$ That question is asking about $\lfloor x\rfloor$, whereas this is about $[x]$ $\endgroup$ Jun 17, 2020 at 18:40
  • $\begingroup$ math.stackexchange.com/questions/2395264/… $\endgroup$
    – Martin R
    Jun 17, 2020 at 18:44

1 Answer 1


It looks like the greatest integer (also known as floor) function.

It can also be denoted as $\lfloor 5.9\rfloor$.


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