Possible Clues:

• It means a million times more to us than 3
• One million million million
• Might so very many get it back on around the stream?
• What the prefix "tera" means
• A million million or a million million million
• Huge number not coming back over stream at one
• A great many unwell in Eastern state, nursed by rather fewer
• That's an awful lot of birdsong on island first
• Ten to the power 12
• An enormous number freely roll in it