Subcategories

• Module 5 Day 6 Challenge Part 1

  Trailing Zeroes in a Factorial

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  L

  The question at the end of the video is "For how many values of n is rounding down of n/5 equal to 28?" If n is any real number in the interval [140,145) then this particular n would satisfy this question. Thus, the answer should just be infinity, for there are an infinite number of ways to satisfy n being in the range of that interval.

• Module 5 Day 6 Challenge Part 2

  The Round Down / Floor Function

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  Only able to get audio for this lesson, no video images so could not attempt the question. All other lessons replaying ok.

• Module 5 Day 6 Challenge Part 3

  Finding Powers of 5

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• Module 5 Day 6 Challenge Part 4

  Patterns in the Powers of 5

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  (Slowest) Bruteforce method:
  def trailing_zeroes_bf(n):
  import math
  count=0
  for i in str(math.factorial(n))[::-1]:
  if i=='0':
  count+=1
  else:
  break
  return count

  (Second fastest) Count 5s:
  def trailing_zeroes_5(n):
  count=0
  power=[i for i in range(100) if 5i<=n][::-1]
  for i in range(1,n+1):
  for pwr in power:
  if i%(5pwr)==0:
  count+=pwr
  break
  return count

  (Fastest) Divide rounded quotient by 5:
  def trailing_zeroes_improv5(n):
  import math
  count=0
  start=math.floor(n/5)
  while True:
  count+=start
  start=math.floor(start/5)
  if start==0:
  return count

  The method taught really is more efficient

• Module 5 Day 6 Your Turn Part 1

  Trailing Zeroes in a Binomial Coefficient

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• Module 5 Day 6 Your Turn Part 2

  Trailing Zeroes in a Binomial Coefficient

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• Module 5 Day 6 Your Turn Part 3

  Trailing Zeroes in a Binomial Coefficient

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