Sum of Digits | international mathematical olympiad 1975 problem 4

#IMO #Math #MathOlympiad

Here is the solution to IMO 1975 Problem 4!!

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I share Maths problems and Maths topics from well-known contests, exams and also from viewers around the world. Apart from sharing solutions to these problems, I also share my intuitions and first thoughts when I tried to solve these problems.

[divyanshusingh]

Hey, why don't you launch a course on number theory? It would be so beneficial

[CreativeMathProblems]

if u have a_{n+1} = S(a_n), the sequence converges very very very fast and hence making bounds (even if they are loose) will always help in solving these problems

[hamu]

Very clearly explained. Thank you, I learned something new

[nawfalebaqa]

very good explanation, the exercise is fascinating! i really would love if these kind of videos were available when i was in high school. the new generation is lucky!

[math]

beautifully done, you explained it well, understand the method now

[staren]

I might be missing something obvious here... but where did "at most 3+9" come from ? 9 is most likely from the mod9, but the 3...?

[theevilmathematician]

Hello letsthinkcritically, I would like to suggest a beautiful, yet difficult IMO problem. It is Problem 2 from the 2011 IMO and it was surprisingly the hardest problem in the contest, even harder than Problem 6.

[alainrogez]

I struggle with your explanations. Where this "at most" come from? Some stuff that you wrote came from nowhere.

[lawlietl]

Fact: 4444^4444 have 16211 digits and your last four digits is 1696.

[devkajla]

I am from INDIA
plz give some more tricks of jee advance papers plz
you are doing a great work

[djwlmmn]

Hello! I would like to learn a bit more about homogenization in inequalities. And I saw a video on your channel, where you talk abot this method. Could you tell me, where can I take some problems, which can be solved with the help of this method?

[Aramil]

3:36 I don't get it, he says "the sum of digits of 4444 is 7" but that's not true, it's 16. What is going on?

[karankumar-kmgi]

How did he find the number of digits ?

[EndemikBitki-xcli]

son dalı az önce yakmıştım, yeni paket almaya gidiyorum.

[aayushmishra]

This type of problem is in Pathfinder for maths Olympiad also .so it was pretty simple for me

[rocky]

I think you need to be more original with your problem selection. Your overlap with Michaelpenn's channel is getting more and more obvious.

[alainrogez]

I have to give you a dislike. For the next time, I beg you, explain your results.