Question:
How many two-digit numbers, with a non-zero digit in the units place, are there which are more than thrice the number formed by interchanging the positions of its digits?
- 5
- 6
- 8
- 7
Correct Answer: 6
Let 'ab' be the two digit number. Where b \( \ne \) 0.
On interchanging the digits, the new number will be ‘ba’
As per the condition 10a+b > 3×(10b + a)
7a > 29b
For b = 1, a = {5, 6, 7, 8, 9}
For b = 2, a = {9}
For b = 3, no value of 'a' is possible.
Hence, there are a total of 6 such numbers
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