If the 9 digit number 807x6y9z8 is divisible by 99, the value of
x+y+z=?
Answers
Step-by-step explanation:
SOLUTION
TO DETERMINE
If the 9 digit number 807x6y9z8 is divisible by 99, the value of x+y+z
CONCEPT TO BE IMPLEMENTED
Divisibility by 9 :
A number is divisible by 9 if the sum of digits is divisible by 9.
Divisibility by 11 :
A number is divisible by 11 if the difference of the sum of the digits at even places and the sum of the digits at odd places is divisible by 11.
EVALUATION
Here the given number is 807x6y9z8
Since the number is divisible by 99
So the number is divisible by both 9 and 11
As 807x6y9z8 is divisible by 9
So sum of digits is divisible by 9
Sum of the digits = 38 + x + y + z
⇒ 38 + x + y + z is divisible by 9 - - - (1)
Again 807x6y9z8 is divisible by 11
Then the difference of the sum of the digits at even places and the sum of the digits at odd places is divisible by 11.
Thus
( 0 + x + y + z ) - ( 8 + 7 + 6 + 9 + 8 ) is divisible by 11
⇒ x + y + z - 38 is divisible by 11 - - - - (2)
(1) and (2) holds when x + y + z = 16
FINAL ANSWER
x + y + z = 16
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