No, I think we all learned that multiplication is commutative in late elementary school, and obviously that’s an important thing to know.
But I think the original post tried to make it out to be some magical mathematical trick, and I really don’t understand that. Maybe I misunderstood the post.
Edit: wow, “commutative” is a really hard word to spell.
…I mean, yeah? If the number is 50 or 10 that works out great. But let’s try that with 7% of 13. Now it’s 13% of 7. Just like you said, “much easier to calculate.”
Okay, choosing prime numbers was intentionally mean on my part. But 3% of 9 becomes 9% of 3. 4% of 2 becomes 2% of 4. Can anyone honestly look me in the eye and tell me that this tip has helped them out in any meaningful way?