– identically equal,
– approximately equal,~ – approximately,
0.(12345) – the repeating decimal with the period 12345,
N – the set of natural numbers,
Z – the set of whole numbers (integers),
R – the set of real numbers,
– an empty set,
– an infinity sign,
– an element x belongs to a set X,
– an element x doesn't belong to a set X,X 
Y – a set X is a subset of a set Y,
Y – a set X is a subset of a set Y,
– a union of sets X and Y,
– an intersection of sets X and Y,X \ Y – a symmetric difference of sets X and Y,
{ un } – a sequence with a general term un ,
[ a, b ] – a numerical segment,
– numerical semi-segments (semi-intervals),( a, b ) – a numerical interval,
– a scalar product of vectors 
,
– a vector product of vectors 
,==> – it follows,
<=> – equivalent,
– perpendicular,
– parallel,
– a triangle ABC,
– a function and its derivative.
