Why was the Calculator Invented?

It makes it easier to deal with $(2+(2\times 10^{-3}))^{6}$

Using binomial expansion

$(2+(2\times 10^{-3}))^{6}=\binom{6}{0}(2)^{6}(2\times 10^{-3})^{0}+\binom{6}{1}(2)^{5}(2\times 10^{-3})^{1}+\binom{6}{2}(2)^{4}(2\times 10^{-3})^{2}+\binom{6}{3}(2)^{3}(2\times 10^{-3})^{3}+\binom{6}{4}(2)^{2}(2\times 10^{-3})^{4}+\binom{6}{5}(2)^{1}(2\times 10^{-3})^{5}+\binom{6}{6}(2)^{0}(2\times 10^{-3})^{6}$

$=64+6(32)(2\times 10^{-3})+15(16)(4\times 10^{-6})+20(8)(8\times 10^{-9})+15(4)(16\times 10^{-12})+6(2)(32\times 10^{-15})+64\times 10^{-18}$

$=64+0.384+0.000\,960+0.000\,001\,280+0.000\,000\,000\,960+0.000\,000\,000\,000\,384+0.000\,000\,000\,000\,000\,064$

$=64.384\,961\,280\,960\,384\,064=A$

Adding the digits of $A$

$6+4+3+8+4+9+6+1+2+8+0+9+6+0+3+8+4+0+6+4= \mathbf{91}$