0.9^18 _hot_ -

( 0.9^2 = 0.81 ) ( 0.9^4 = (0.81)^2 = 0.6561 ) ( 0.9^8 = (0.6561)^2 = 0.43046721 ) ( 0.9^{16} = (0.43046721)^2 = 0.1853020188851841 )

So:

Let’s calculate ( 0.9^{18} ) step-by-step. 0.9^18

[ 0.9^{18} \approx 0.1500946353 ]

( 0.9^{18} = 0.9^{16} \times 0.9^2 ) ( = 0.1853020188851841 \times 0.81 ) 0.9^18

We can compute stepwise: