The question is fundamentally nonsensical, much like questioning the existence of the number 42 within a calculator.
Firstly, consider the nature of numbers and mathematical truths. The number 42, for instance, exists as a concept within the realm of mathematics, independent of any physical or digital representation. A calculator can perform operations involving 42, displaying it on its screen, but the number's existence is not contingent upon this representation. Whether or not a calculator is switched on, or whether 42 is actively being displayed, does not affect the number's existence within the mathematical framework. The calculator merely accesses and manipulates a reality (the mathematical truth of 42) that exists independently of the device.
Applying this analogy to the universe and the concept of a simulation, if it is possible for our universe to be simulated, this implies that the universe can be fully described by a set of mathematical rules or computational algorithms. These rules or algorithms define all possible states and outcomes of the universe, much like how the principles of mathematics define the existence and properties of numbers.
Therefore, the existence of our experiences, consciousness, and the universe itself does not depend on whether a simulation is actively being run. Just as the number 42 does not cease to exist when a calculator is switched off, our universe and everything in it does not require an active simulation to exist. The potential for our universe to be simulated indicates that its essence is embedded in the underlying mathematical or computational structure, independent of any physical instantiation of that simulation.
Asking whether we are living in a simulation becomes akin to asking whether the number 42 exists within your calculator—it misses the point. The existence of the universe, like the existence of 42, is a facet of its mathematical or computational structure, not its representation or simulation in a particular medium. Thus, the question of living in a simulation overlooks the fundamental nature of existence as something that transcends physical or simulated reality, rooted instead in the abstract, yet profoundly real, domain of mathematical possibility.
Back to your analogy, if you divide 42/9, a calculator will say something like 4.66666667, which is only an approximation to the true answer. So it makes a difference what substrate the number exists in.
If we are in a simulation and could figure out exactly how the approximation is done, we might find some useful tricks to do with it. Most practical physics simulators we have today (say for simulating robots) can be triggered into producing wildly wrong results, where energy isn't conserved. That would be cool.