"[...], and it’s dimensionless, so you can’t easily check if you forgot to divide or multiply by it." For what it's worth, it's often the case that a factor of

"[...], and it’s dimensionless, so you can’t easily check if you forgot to divide or multiply by it." For what it's worth, it's often the case that a factor of 2pi is the difference between something being in terms of cycles/sec or rad/sec. In an experimental context, it usually isn't too difficult to judge which of these "units" a quantity you're looking at is in...