Hi @RZ923,
You are totally right that the closest number that Prof. Loh can use to get the answer \(100\) times \(2\pi\) is \(628.\) Actually, \(2\pi\) is equal to \(2\times 3.14=6.28.\)
However, Prof. Loh didn't choose the number \(710\) for the purpose of geting an answer that is close to \(100\) (but it's still a good bonus). He did it for a different reason: to illustrate the integers \(710\) and \(226,\) which we can use to get the number that will be very close to \(\pi:\) \(\frac{710}{226}=\frac{355}{113}={\color{darkred}3.14159292}\approx 3.141592654...= \pi.\)
But you have a great observation here! It's awesome! So, keep it up 🙂