Quantitative Aptitude – Modern Maths – P and C – How many two-digit numbers

Slot -2 – Quantitative Aptitude – Modern Maths – P & C – How many two-digit numbers

 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?

a) 6
b) 8
c) 7
d) 5

Answer: 6

Solution:
Let the number is ab so
10a+b >3(10b+a)
7a>29b
a/b>29/7
So the possible pair of (a,b) are (5,1), (6,1), (7,1) , (8,1) , (9,1) & (9,2)
Thus total 6 such numbers are possible.

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