Newt[x_]  =  x/2  +  1/x

x  =  2

x  =  Newt[x]

N[%19, 20]

FindRoot[{t + u == 1, 
        t - u == 0}, {{t, 1}, {u, 1}}]

FindRoot[{t + u == 1, t - u == 0}, {t, 1}, {u, 1}]

N[(∫_0^π)(Sin[t])^4/t^2 \[DifferentialD]t]

NSolve[t^2 - 2 == 0, t]

Gamma[3]

Gamma[5]

Gamma[0.5]

Gamma[1/2]

(∑_(i = 1)^n) i^10

Prime[3]

Prime[4]

Prime[5]

Prime[10^11]

A  = {{1, 2},  {3, 4} }

MatrixForm[A]

Eyevalues  =  Eigenvalues[A]

N[First[Eyevalues]^2]

N[Last[Eyevalues]^2]

Solve[t^2 - a == 0, t]

t  /.  First[%59]  /.  a  ->  4

Plot3D[Exp[-(t^2 + u^2)], {t, -3, 3}, {u, -3, 3}, 
      PlotRange  -> {0, 1}]