Question
How many of the following numbers are divisible by 3 but not by 9 ?
2133, 2343, 3474, 4131, 5286, 5340, 6336, 7347, 8115, 9276
Answer: Option B
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Marking(`sqrt`)those which are divisible by 3 but not by 9 and the others by (`x`), by taking he sum of digits , we get:
2133 `rarr` 9 (`xx`). 2343 `rarr`12 (`sqrt`), 3474 `rarr`18 (`xx`), 4131 `rarr` 9 (`xx`), 5286 `rarr` 21(`sqrt`),
5340 `rarr` 12 (`sqrt`), 6336 `rarr`18 (`xx`), 7347 `rarr` 21 (`sqrt`), 8115 `rarr`15 (`sqrt`), 9276 `rarr` 24 (`sqrt`)
Required number pf numbers = 6
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