If the eight -digit number 342x 18y6 is divided by 72, then what is the value of √(9x + y), for the largest value of y?
Show answer & explanation
Correct answer: D
Explanation
Correct Answer is option 4 i.e. 6
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Concept |
Understanding |
Application |
Fair calculation |
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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.: 342x18y6 is divisible by 72
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Last 3 digits 8y6 must be divisible by 8: Hence, y = 9 or 5 or 1 We will consider the largest value of y i.e. 9. Divisibility by 9: [3 + 4 + 2 + x + 1 + 8 + 9 + 6] should be Divisible by 9. [33 + x] should be Divisible by 9. Hence, x = 3 Now, √(9x+y)=√(27+9) = 6
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√(27+9) = √36 = 6
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