▁four ▁se lections ▁in ▁a ▁Yan kee , ▁for ▁example , ▁when ▁the ▁potential ▁over round ▁on ▁a ▁simple ▁four fold ▁of ▁races ▁with ▁individual ▁books ▁of ▁ 1 2 0 % ▁is ▁over ▁ 1 0 7 % ▁( a ▁book ▁of ▁ 2 0 7 %). ▁This ▁is ▁why ▁book m akers ▁offer ▁bet s ▁such ▁as ▁L ucky ▁ 1 5 , ▁L ucky ▁ 3 1 ▁and ▁L ucky ▁ 6 3 ; ▁offering ▁double ▁the ▁odd s ▁for ▁one ▁winner ▁and ▁increasing ▁percentage ▁bon uses ▁for ▁two , ▁three ▁and ▁more ▁w inners . ▁ ▁In ▁general , ▁for ▁any ▁accum ulator ▁bet ▁from ▁two ▁to ▁i ▁se lections , ▁the ▁combined ▁percentage ▁over round ▁of ▁books ▁of ▁B 1 , ▁B 2 , ▁... , ▁Bi ▁given ▁in ▁terms ▁of ▁dec im als , ▁is ▁calculated ▁by ▁B 1 ▁× ▁B 2 ▁× ▁... ▁× ▁Bi ▁× ▁ 1 0 0 ▁− ▁ 1 0 0 . ▁E . g . ▁the ▁previously ▁mentioned ▁four fold ▁consisting ▁of ▁individual ▁books ▁of ▁ 1 2 0 % ▁( 1 . 2 0 ) ▁gives ▁an ▁over round ▁of ▁ 1 . 2 0 ▁× ▁ 1 . 2 0 ▁× ▁ 1 . 2 0 ▁× ▁ 1 . 2 0 ▁× ▁ 1 0 0 ▁− ▁ 1 0 0 ▁= ▁ 1 0 7 . 3 6 %. ▁ ▁S ett ling ▁winning ▁bet s ▁ ▁In ▁sett ling ▁winning ▁bet s ▁either ▁decimal ▁odd s