12. REDUCE YOUR CALCULATION BY WATCHING THE FEATURES OF THE EXPRESSION OR THE EQUATION ETC.

For example, about a machine, the more parts bring the more faults. In a similar way, at solving, if you have many calculating, you may get some errors. The probability of error will rise.

So, make efforts to reduce your calculation. For example,
401×399=(400+1)×(400-1)=400^2-1^2. (“^2” means square. 4^2=16.)
It is easy and safe, isn’t it?

See you next.

Nasuno Kumao