1.00001≈1
1≤1,1≤2
2≥1,1≥1
2⋅n=2n
15÷3=5
∑i=1nxi
∑i=13xi=x1+x2+x3
∏i=1nxi
∏i=13xi=x1⋅x2⋅x3
9=3,327=3
∣−1∣=1
0!=1,3!=1×2×3=6
Pkn=(n−k)!n!
P38=(8−3)!8!=336
Ckn,(kn)
Ckn=(kn)=k!Pkn=k!(n−k)!n!
C38=(38)=3!×(8−3)!8!=56
1∧1=1,1∧0=0
1∨0=1,0∨0=0
1⊕0=1,0⊕0=0
1∈{1,2,3}
4∈/{1,2,3}
∀x∈{1,2,3}
∅⊂{1}
{1,2,3}∩{2,3,4}={2,3}
{1,2,3}∩{2,3,4}={1,2,3,4}
{1,2,3}⊆{1,2,3}
{1,2,3}⊇{1,2,3}
{4}⊈{1,2,3}
{1,2,3}⊉{0}
{1}⊂{1,2,3}
{1,2,3}⊃{1}
{1,2,3}\{3,4,5}={1,2}
+∞,−∞
−∞<0<+∞