Question
The number 7490xy is divisible by 90. Find out (x + y).
Answer: Option D
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90 = 10 × 9
7490xy is divisible by 90. Since 10 and 9 are factors of 90,
7490xy is divisible by 10 and 7490xy is divisible by 9
7490xy is divisible by 10. We know that A number is divisible by 10 if the last digit is 0.
Hence y = 0
Thus we have the number 7490x0 which is divisible by 9
=> sum of its digits of 7490x0 is divisible by 9
=> 7 + 4 + 9 + 0 + x + 0 is divisble by 9
=> 20 + x is divisible by 9 (Where x is a digit)
=> x = 7
Hence, (x + y) = (7 + 0) = 7
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