# Qiskit textbook: Shor's algorithm

The Qiskit textbook shows the following circuit for implementing the phase $$(\frac{s}{r})$$ estimation stage of Shor's algorithm for factorizing 15: My understanding is that the register of qubits 8-11 should be initialized to the state $$|1\rangle$$ which is the sum over $$s \in \{0, .., r-1\}$$ of the eigenstates$$\frac{1}{\sqrt r}\sum_{k=0}^{r-1}e^{-\frac{2\pi i s k}{r}}|a^k \mod N\rangle$$ of the modular multiplication operator $$U|y\rangle = |ay \mod N \rangle$$.
But the 4-qubit representation of $$|1\rangle$$ is $$|0001\rangle$$ and not $$|1000\rangle$$.
So, shouldn't we set $$q_8$$ (the lsb of the modular exponentiation circuits) to 1 instead of $$q_{11}$$?
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