Answer :
The number of different ways to choose the ten digit number is divisible by 9 is 11 ways .
In the question ,
it is given that ,
the number is 631872ab ;
and also the number is divisible by 9 ,
we know that the number is divisible by 9 , then the sum of digits is also divisible by 9 .
the sum of the digits is = 27 + a + b .
for 27 + a + b to be divisible by 9 , a+b should be divisible by 9 .
So , we can choose a+b = 0 or a+b = 9 .
for a+b = 0 , the ordered pair is (0,0) that is 1 way
for a+b = 9 , the ordered pair for (a,b) is (0,9) , (1,8) , (2,7) , (3,6) , (4,5) , (5,4) , (6,3) , (7,2) , (8,1) and (9,0) that is 10 ways .
So , the total number of possible pairs is 1 + 10 = 11 ways .
Therefore , the number of different ways of selection is 11 ways .
Learn more about Number here
https://brainly.com/question/24187022
#SPJ4