Find position of point after scaling (OpenGL and C++)

Question

I've created a program that draws points to the screen in OpenGL (It draws the letter "X" at a specific point). The drawing is then scaled based on user input.

if (GetAsyncKeyState(VK_UP))
{
    /*"zoom" is a global float variable*/
    zoom += 0.005;
}

glScaled(1 + zoom, 1 + zoom, 1);

I want to find the new position of the points relative to the screen (i.e. A point may be drawn at (100, 100) but after scaling it may be somewhere like (150, 200) with regard to the screen coordinates, but the rasterisation values are always the same, in this case (100, 100)). Is there a function in OpenGL that can return the new coordinates of a point based on specific scaling?