If an eleven-digit number 5y5888406x6 is divisible by 72, then what is the value of (9x – 2y), for the least value of x?
Show answer & explanation
Correct answer: C
Explanation
Correct Answer is option 3 i.e. 3
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Concept |
Understanding |
Application |
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Divisibility rule: If a number is divisible by 72 it must be divisible by 8 and 9 Divisibility by 8: Last 3 digits must be divisible by 8. Divisibility by 9: Sum of all digits should by divisible by 9 |
Eight-digit no.: 5y5888406x6 is divisible by 72
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Last 3 digits 6x6 must be divisible by 8: Hence, y = 9 or 5 or 1 Least value of x i.e. 1: Divisibility by 9: [5 + y + 5 + 8 + 8 + 8 + 4 + 0 + 6 + 1 + 6] should be Divisible by 9. [51 + y] should be Divisible by 9. Hence, y = 3 Hence, 9x – 2y = 9 × 1 – 2 × 3 = 9 – 6 = 3 |