x = -5:.1:5;
y1 = x.^2;
y2 = x.^3;
y3 = sin(x);

% you can name your figure in your style, the following
% first plots figure 7, then figure 2, then figure 3
figure(7), 
  plot(x,y1), title('plot of x^2')
figure(2),
  plot(x,y2), title('plot of x^3')
figure(3),
  plot(x,y3), title('plot of sin(x)')