I'm trying to figure out how many sts to cast on for someone with a bigger head- the pattern calls for 113 cast on for a 19'' hat (says stretches to fit,but prob not to 24'', right?) The pattern is in multiples of five ribbing-k2 p1 plus k2, so if my test swatch was 5sts per in, how many extra do u think I should cast on? 24x5=120, but that is only 7 more than original...help I'm having a math meltdown!