Float formatting (quii#262)

In this example should be %f format to get the error exactly like further in the text

Author: aivchen

math.md

@@ -1022,7 +1022,7 @@ func secondHand(w io.Writer, t time.Time) {
 p = Point{p.X * secondHandLength, p.Y * secondHandLength} // scale
 p = Point{p.X, -p.Y} // flip
 p = Point{p.X + clockCentreX, p.Y + clockCentreY} // translate
-fmt.Fprintf(w, `<line x1="150" y1="150" x2="%.3f" y2="%.3f" style="fill:none;stroke:#f00;stroke-width:3px;"/>`, p.X, p.Y)
+fmt.Fprintf(w, `<line x1="150" y1="150" x2="%f" y2="%f" style="fill:none;stroke:#f00;stroke-width:3px;"/>`, p.X, p.Y)
 }
 
 const svgStart = `<?xml version="1.0" encoding="UTF-8" standalone="no"?>