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53.How many three digit numbers are divisible by 13 and having middle digit(a) 55?(d) 13(b) 7(c) 10 |
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Answer» For a number to be divisible by 13, we have a small trick.sayxyzis the number whenxis any digit number whiley&zare single digits then (4*x - yz) should be divisible by 13. For 3 digit numberxis single digit as well. Without any logics we can say that upper bound is 9 for our answer. According to given questionyis fixed as 5.xlies from 1 to 9 both included.zlies from 0 to 9 both included. Now lets go one by one : 15z : to satisfy above trick z can be 6. 25z : No value of z exists. Similarly 351,455,559,650,754,858 satisfies while 95z will not. So the answer is7. |
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