Question

Answer 1

\(1001^2=\left(1000+1\right)^2=1000^2+2.1000+1=1000000+2000+1=1002001\\ ---\\ 99^2=\left(100-1\right)^2=100^2-2.100.1+1=10000-200+1=9801\\ ---\\ 29,9.30,1=\left(30-0,1\right)\left(30+0,1\right)=30^2-\left(0,1\right)^2=900-0,01=899,99\\ ----\)