REVIEW: q1.26 -- by explicitly multiply expmod expression, too much calculation has executed

[a12813f811] says.... "study 2012-01-16. need to review expmod"
REVIEW: q1.46 -- iterative improvement

[a8ecd6f33]: q1.46. need to review it
REVIEW: q2.29 -- binary mobile improvement

[7bc56124ff] says.. "2012-03-26 study memo. q2.29 is worth reviewing."