Find all possible values of digit a, given that the six-digit number 3529a2 is divisible by
I don't know if this is by all of these, but I'm assuming the a,b,c,d are not constraints for one question but multiple questions.
(a) $3 + 5 + 2 + 9 + a + 2 = 3n \Rightarrow 21 + a = 3n \Rightarrow a=0; a=3; a=6; a=9$
(b) $a+2 = 4n \Rightarrow a = 2; a = 6$
(c) All values of (b) that are also in (a), or vice versa $\Rightarrow a = 6$
(d) All values of (c) that are also in (a), or vice versa $\Rightarrow a = 6$