Question

(9999)squre
multiply without directly multiply

Answer 1

(10000-1)^2

=10000^2+1^2-2*10000*1

=100000000+1-20000

Answer 2

(9999)^2

(10000-1)^2. { (a-b)^2= a^2+b^2-2ab}

(10000)^2+(1)^2-2(10000)(1)

100000000+1-20000

=99980001