Reference

UNIX productivity tips
http://www-128.ibm.com/developerworks/aix/library/au-productivitytips.html

via

i d e a * i d e a - UNIX使いのパフォーマンスをあげる小技コマンド
http://www.ideaxidea.com/archives/2006/09/unix.html

Reference

Wikipedia - ネイピアの骨

via

i d e a * i d e a - かけ算2.0
http://www.ideaxidea.com/archives/2006/09/20_6.html