How to solve (-98) * (-9)+98 using suitable properties. Please tell fast.

Answer :

We know  :

- $\times$ -  = +

-  $\times$ +   =  -

And we have  : ( - 98 ) $\times$ ( - 9 )  + 98   , So  

= 98 $\times$  9  $\times$  -  1 $\times$  -  1  + 98

= 98 $\times$ 9  +  98 

Now we apply distributive property and get

= 98 (   9 + 1 )

=   98  $\times$ 10 

= 980                                                                         ( Ans )