Now, A little bit harder

This is continuous from the previous article. If you havent read it, please read it first before you try this. :)

The inverse rule could be used to do many other multiplications.
To multiply 99x101,
it is the same as (100+1)(100-1)=10000-1=9999

Similarly, 97*103 = 9991,
or84*86=852-12=7225-1=7224