list = {1, 2, 3, 4, 5}

3  list

list^2

1/list

x^list

Sin[list*Pi/3]

a1 = {-1, 2, -3, 4, -5};
a2 = {1, 3, 5, 7, 9};
a3 = {2, 4, 6};

a1 + a2

a1 + a3

a1*a2

Length[a1]

Length[a3]

a1[[1]]

a1[[2]]

Join[a1, a2]

Join[a1, a3]

Union[a1, a3]

a1 . a2

b1 = {{1, 2}, {3, 4}};
b2 = {{2, 3}, {4, 5}};

b1  // MatrixForm

b1 . b2

Transpose[{a1}]

Transpose[a1]

Range[10]

Range[-10, 10]

a4 = Range[-1, 1, 1/10]

Sin[a4 Pi]

%  // N

Table[i, {i, 1, 10}]

Table[i^2, {i, 1, 10}]

Range[10]^2

Table[i + j, {i, 1, 10}, {j, 1, 8}]

%  // MatrixForm

NullSpace[%]

A = {{3, -1}, {2, 5}, {0, -2}} . {{1, 2, 3}, {2, 3, 
            4}}

A  // MatrixForm

jc = JordanDecomposition[A]

%  // MatrixForm

jc[[1]]

%  // MatrixForm

jc[[2]]

%  // MatrixForm

B = Table[i^2 + i*j + j^2, {i, 1, 6}, {j, 1, 6}]

B  // MatrixForm

NullSpace[B]

6 - 3

Random[Integer, {0, 99}]

A1 = Table[Random[Integer, {0, 99}], {i, 1, 100}]

Select[
      A1, # == 10  ||  # == 43  ||  # == 
            83  &]

Sort[A1]

A1 = Table[Random[Integer, {0, 99}], {i, 1, 100}]

Select[
      A1, # == 10  ||  # == 43  ||  # == 
            83  &]

Length[%]