KVPY2017MathematicsSets and Relations
Consider the set A of natural numbers n whose units digit is nonzero, such that if this units digit is erased, then the resulting number divides n . If K is the number of elements in the set A , then.
Options
- AK is infinite
- BK is finite but K>100
- C25 K 100
- DK < 25
Correct answer
D. K < 25
Step-by-step solution
array l Such numbers are =9 from 11 to 19 array 4 i.e. (22,24,26,28) 3 i.e. (33,36,39) 2 i.e. (44,48) 5 i.e. (55,66,77,88,99) 23