Please explain me (100%21)

Answer 1

% is a modulus operator and it gives us the remainder of a division operation

for example:
100%21 = 16

___________
divisor | divident | Quotient
- - - - - - - -
Remainder
______
21 | 100 | 4
84
- - - - -
16

Answer 2

Thank you very much!

Answer 3

Can you tell me your name?

Answer 4

Where are you from?