Actionscript:
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var canvas:BitmapData = new BitmapData(400, 400, false, 0xCCCCCC);
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addChild(new Bitmap(canvas));
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drawCircle(200,100, 50);
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// y, y radius, color
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function drawCircle(xp:Number,yp:Number, radius:Number, col:uint =0x000000):void {
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var balance:int;
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var xoff:int;
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var yoff:int;
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xoff=0;
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yoff=radius;
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balance=- radius;
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while (xoff <= yoff) {
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canvas.setPixel(xp+xoff, yp+yoff, col);
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canvas.setPixel(xp-xoff, yp+yoff, col);
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canvas.setPixel(xp-xoff, yp-yoff, col);
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canvas.setPixel(xp+xoff, yp-yoff, col);
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canvas.setPixel(xp+yoff, yp+xoff, col);
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canvas.setPixel(xp-yoff, yp+xoff, col);
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canvas.setPixel(xp-yoff, yp-xoff, col);
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canvas.setPixel(xp+yoff, yp-xoff, col);
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if ((balance += xoff++ + xoff)>= 0) {
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balance-=--yoff+yoff;
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}
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}
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}
The above demos a circle drawing algorithm. This will draw an outlined circle with no fill. This implementation doesn't use multiplication.
Using setPixel to draw primitive shapes can be a good learning experience. I found this basic implementation of the Bresenham Circle algorithm a few years back and lost the original link.... I dug around for a good hour trying to find the original but to no avail. So if someone recognizes this interesting implementation .... let me know 
The original code was written in java I think.
If your curious. The standard implementation I keep finding online looks something like this:
Actionscript:
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// ported from http://www.codeuu.com/Bresenham_Circle
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function drawCircle(cx:Number, cy:Number, r:Number, col:uint):void{
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var xp:int = 0, yp:int= r ;
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var d:int = 3 - (2 * r);
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while(xp <= yp){
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canvas.setPixel(cx+xp,cy+yp,col);
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canvas.setPixel(cx+yp,cy+xp,col);
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canvas.setPixel(cx-xp,cy+yp,col);
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canvas.setPixel(cx+yp,cy-xp,col);
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canvas.setPixel(cx-xp,cy-yp,col);
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canvas.setPixel(cx-yp,cy-xp,col);
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canvas.setPixel(cx+xp,cy-yp,col);
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canvas.setPixel(cx-yp,cy+xp,col);
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if (d<0){
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d += (4*xp)+6;
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}else{
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d += (4*(xp-yp))+10;
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yp -= 1;
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}
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xp++;
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}
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}
I did a few speed tests against the first one that doesn't make use of multiplication and it is only ever so slightly faster....