1.lg is a common logarithmic symbol based on 10. If there is any number a (a >; 0) is the base, which is represented by log, and the logarithm with the base of e(=2.7 183) is called natural logarithm, which is represented by ln, such as LG2, LOGA8, LN 10. ...

2.！ It's a factorial symbol, 4! = 1×2×3×4=24; n！ = 1*2*3*...*(n- 1)*n

(The product of n integers starting from 1 is called the factorial of n, and n! Representative)