5. 4^5a
6. 6.8x10^-6
7. (5^2)/2^19
https://www.facebook.com/1818197078408095/posts/2146115788949554/
https://www.facebook.com/1818197078408095/posts/2149397451954721/
https://www.facebook.com/1818197078408095/posts/2152835318277601/
ลองดูสามคลิปนี้นะ
