>>40 fails at percentages.

If you add 6% to 100 you get 106.
If you add 6% to 1 you get 1.06
If you add 6% to 1% you get 1.06%
If you add 6% to 0.01% you get 0.0106%

% is really just shorthand for 1/100.

Adding N% is really the same as multiplying by (1+N/100).