I dont understand your math. Sure, utilization + payment history together account for 65% of total FICO score, but each are based on both individual cards and combined. A bad history, either in terms of payment baddies or high utilization, on a sinngle card does not account for 65% of total score. As for length of credit, it is based on both average and oldest, so the oldest card wont account by itself for 15% of total FICO.