Question : If the five-digit number 235xy is divisible by 3,7 and 11, then what is the value of (3x - 4y)?
Option 1: 10
Option 2: 8
Option 3: 9
Option 4: 5
Correct Answer: 10
Solution :
Given,
Five-digit number 235xy is divisible by 3, 7, and 11
Divisibility rule of 3: The sum of its digit is divisible by 3.
Divisibility rule of 7: To make a pair of 3 from the unit digits then subtract the leftover pair, The result is divisible by 7.
Divisibility rule of 11: The difference between the sum of an odd place and an even place is zero or multiples of 11. The result is divisible by 11.
235xy
⇒ For 3,
⇒ For 11, (7 +
⇒
⇒ For 7, 562 - 023 = 539
it is also divisible by 7
⇒ number = 23562 and
now,
⇒ 3
Hence, the correct answer is 10.
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