<s>[INST] $16^{18}+16^{18}+16^{18}+16^{18}+16^{18}=4^x$ without a calculator How to  solve the following equation without using calculator 
$$16^{18}+16^{18}+16^{18}+16^{18}+16^{18}=4^x$$
 [/INST] $16^{18}+16^{18}+16^{18}+16^{18}+16^{18}$
$=5\times 16^{18}$ 
$= 5\times {4^2}^{18} $
$= 5\times 4^{2\times 18} = 5\times 4^{36} = 4^x$ 
$ 5\times 4^{36} = 4^{\log_4{5}} \times 4^{36} $
$= 4^{\log_4{5} +36}$
$\rightarrow x= \log_4{5} +36$
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