So I have to figure out if $1.23456$ is constructible. I think that it's not constructible since:
I know that this is $\frac{123456}{100000}$ so this goes into $\frac{2^6*3*643}{2^55^5}$ and the Fermat Primes are repeated in the denominator so then it's not constructible.
Am I overthinking this? Is it constructible?