Find the greatest possible value of (a + b) for which the 8 digit number 148b205a is divisible by 15.

13

The number is 148b205a.

15 =  3   x  5

According to Divisibility rule of 5 , unit digit of the number should be 0 or 5.

Therefore, a = 0 or 5

ATQ, we have to find the greatest value, hence a = 5

According to Divisibility rule of 3 , sum of all digit of the number should be multiple of 3.

Therefore, Sum of digits = 1 + 4 + 8 + b + 2 + 0 + 5 + 5

                                    = 25 + b

Here,

b should be = 2, 5 or 8

Here, b = 8 (to find the greatest value)

⇒ a + b = 8 + 5 = 13