Brute Force No More

Algebra Level 5

π + π + 1 2016 + π + 2 2016 + + π + 2015 2016 + 1 = ? \large \left \lceil \lfloor \pi \rfloor + \left \lfloor \pi + \dfrac{1}{2016} \right \rfloor + \left \lfloor \pi + \dfrac{2}{2016} \right \rfloor + \cdots + \left \lfloor \pi + \dfrac{2015}{2016} \right \rfloor \right \rceil + 1 =\, ?

Notations : \lfloor \cdot \rfloor denotes the floor function and \lceil \cdot \rceil denotes the ceiling function .


Too hard? Try this .


The answer is 6334.

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3 solutions

Ralph Macarasig
Aug 6, 2016

Using Hermite's Identity ,

n x = x + x + 1 n + x + 2 n + + x + n 1 n \lfloor nx \rfloor = \lfloor x \rfloor + \left \lfloor x + \frac{1}{n} \right \rfloor + \left \lfloor x + \frac{2}{n} \right \rfloor + \dots + \left \lfloor x + \frac{n - 1}{n} \right \rfloor for x R x \in \mathbb{R} and n N n \in \mathbb{N}

π + π + 1 2016 + π + 2 2016 + . . . + π + 2015 2016 + 1 \lceil \lfloor \pi \rfloor + \lfloor \pi + \frac{1}{2016}\rfloor + \lfloor \pi + \frac{2}{2016}\rfloor + ... + \lfloor \pi + \frac{2015}{2016}\rfloor \rceil + 1

= 2016 π + 1 = \lceil \lfloor 2016\pi \rfloor \rceil + 1

= 6333 + 1 = \lceil 6333 \rceil + 1

= 6334 = \boxed{6334}

Raaaalph

R \mathbb{R} .

Manuel Kahayon - 4 years, 10 months ago

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\mathbb{R}

Manuel Kahayon - 4 years, 10 months ago

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thaaaanks hahaha

Ralph Macarasig - 4 years, 10 months ago

good question, had me stumped there. also good reference to doctor who.

Goh Choon Aik - 4 years, 10 months ago

Nice question maybe a bit overrated, but keep it up!

Ashish Menon - 4 years, 10 months ago
Chris Lam
Aug 8, 2016

First post so not sure if this is up to par.

I noted that π + x 2016 \lfloor \pi + \frac{x}{2016}\rfloor would be equal to 3 for all x 1730 x \leq 1730 [which was found by the equation x = 2016 ( 4 π ) x = 2016 * (4 - \pi) .

So that means within the ceiling function, there are 1731 terms (the first π \pi , then the 1730 floors after that) that equal 3's after the floors are applied. 3 1731 = 5193 3 * 1731 = 5193

For x > 1730 x > 1730 , there are 2015 1730 = 285 2015-1730 = 285 terms that equal 4's after the floors are applied. 4 285 = 1140 4 * 285 = 1140

Added together, the ceiling function is 6333. Add the 1, 6334

EDIT: counting error

Same way.!!!

Shreyash Rai - 4 years, 10 months ago

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me too , i guess all naruto fans follow the same method.

A Former Brilliant Member - 4 years, 10 months ago

exactly! Same here as well!

Swagat Panda - 4 years, 10 months ago

i do exactly like you ... excellent

Abdullah Ahmed - 4 years, 10 months ago
Fahim Saikat
Jul 8, 2017

For 0<=n<=1730 , ( π + n 2016 ) = 3 \lfloor(\pi + \frac{n}{2016})\rfloor=3 and 1731<=n<=2015 , ( π + n 2016 ) = 4 \lfloor(\pi + \frac{n}{2016})\rfloor=4

therefore answer is , ( 1730 ( 0 1 ) ) × 3 + ( 2015 ( 1731 1 ) ) × 4 + 1 = 1731 × 3 + 285 × 4 + 1 = 6334 (1730-(0-1))\times3+(2015-(1731-1))\times4+1=1731\times3+285\times4+1=\boxed{6334}

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