Problemas para el boton de envio

[madhatterdef]

aclaro que había olvidado cambiar el id

imagen1=new Image

imagen1.src="top1.png"

imagen2=new Image

imagen2.src="top1.gif"

imagen3=new Image

imagen3.src="top2.png"

imagen4=new Image

imagen4.src="top2.gif"

imagen5=new Image

imagen5.src="top3.png"

imagen6=new Image

imagen6.src="top3.gif"

function cambiar (){
a = document.getElementById("numero").value;

// index 1
if( 30000000<= a && a <= 30289999|
40000000<= a && a <= 40999999|
45000000<= a && a <= 46999999|
48720000<= a && a <= 50099999|
50300000<= a && a <= 50699999|
51500000<= a && a <= 52099999|
53000000<= a && a <= 53099999|
53140000<= a && a <= 53899999|
55200000<= a && a <= 55299999|
55500000<= a && a <= 55539999|
55800000<= a && a <= 55819999|
57000000<= a && a <= 57099999|
57190000<= a && a <= 57899999|
58000000<= a && a <= 58099999|
58190000<= a && a <= 58199999|
58800000<= a && a <= 59099999|
59180000<= a && a <= 59199999|
59900000<= a && a <= 59999999)
return b;
{document.images['top1'].src=imagen2.src}

// index2
else if(41000000<= a && a <=42999999|
47000000<= a && a <=47419999|
50100000<= a && a <=50199999|
51100000<= a && a <=51399999|
53100000<= a && a <=53119999|
54100000<= a && a <=54999999|
55100000<= a && a <=55179999|
55300000<= a && a <=55399999|
55430000<= a && a <=55449999|
55540000<= a && a <=55799999|
55820000<= a && a <=55999999|
56100000<= a && a <=56399999|
56900000<= a && a <=56999999|
57100000<= a && a <=57189999|
58100000<= a && a <=58189999|
58200000<= a && a <=58799999|
59100000<= a && a <=59149999|
59200000<= a && a <=59899999)
return c;
{document.images['top2'].src=imagen4.src}

// index3
else if(43000000<= a && a <=44759999|
50200000<= a && a <=50299999|
50700000<= a && a <=51099999|
51400000<= a && a <=51499999|
52100000<= a && a <=52999999|
53120000<= a && a <=53139999|
53900000<= a && a <=54099999|
55000000<= a && a <=55099999|
55180000<= a && a <=55199999|
55400000<= a && a <=55429999|
55450000<= a && a <=55499999|
56000000<= a && a <=56099999|
56400000<= a && a <=56899999|
57900000<= a && a <=57999999|
59150000<= a && a <=59179999)

{document.images['top3'].src=imagen6.src}

else{ document.images['top1'].src=imagen1.src;
document.images['top2'].src=imagen3.src;
document.images['top3'].src=imagen5.src;

}
}