The following table could be helpul in reducing our calculations.
Memorize the above table so that it can be used during calculations which would reduce the time considerably.
For example if you have to multiply 150 X 6.66%
you can just use 1/15 in place of 6.66%
ie , 150X(1/15) = 10
Like this you can switch between percents ,decimals and fractions to calculate faster.