reserve d,i,j,k,m,n,p,q,x,k1,k2 for Nat,
  a,c,i1,i2,i3,i5 for Integer;

theorem Th24:
  n |^ 2 = n^2
proof
  n |^ 2 = n |^ (1 + 1) .= n |^ 1*n |^ 1 by NEWTON:8
    .= n^2;
  hence thesis;
end;
