Factorials and Trailing Zeros
6 lessons · 5 questions · 1 PYQs
What the exams ask here
- max n with p^n | N!
- zeros at end of N!
- 21^n divides 50! (Indore 2019 Q22); highest power of 24 in 108!
- how many N have N! ending in exactly k zeros; smallest N with k zeros
- zeros at the end of 5 x 10 x 15 ... / 1^1 2^2 ... n^n / 30 x 60 x ... x 30n
Lessons
- Start hereThe idea and the methodFirst lesson of Factorials and Trailing Zeros
- 1.Highest power in factorial1 question + fresh variants
- 2.Trailing zeros1 question + fresh variants
- 3.Composite base: scarcest prime wins2 questionsIndore 20195 min video
- 4.Trailing Zeros: The Inverse Trick1 question5 min video
- 5.Zeros in productsNew numbers every time (templates)