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								---
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								id: 5900f4461000cf542c50ff58
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								title: 'Problem 217: Balanced Numbers'
							 
						 
					
						
							
								
									
										
										
										
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								challengeType: 5
							 
						 
					
						
							
								
									
										
										
										
											2019-08-05 09:17:33 -07:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								forumTopicId: 301859
							 
						 
					
						
							
								
									
										
										
										
											2021-01-13 03:31:00 +01:00 
										
									 
								 
							 
							
								
									
										 
								
							 
							
								 
							
							
								dashedName: problem-217-balanced-numbers
							 
						 
					
						
							
								
									
										
										
										
											2018-09-30 23:01:58 +01:00 
										
									 
								 
							 
							
								
							 
							
								 
							
							
								---
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
									
										
										
										
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								# --description--
  
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
									
										
										
										
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								A positive integer with $k$ (decimal) digits is called balanced if its first $⌈\frac{k}{2}⌉$ digits sum to the same value as its last $⌈\frac{k}{2}⌉$ digits, where $⌈x⌉$, pronounced ceiling of $x$, is the smallest integer $≥ x$, thus $⌈π⌉ = 4$ and $⌈5⌉ = 5$.
							 
						 
					
						
							
								
									
										
										
										
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								So, for example, all palindromes are balanced, as is 13722.
							 
						 
					
						
							
								
									
										
										
										
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								Let $T(n)$ be the sum of all balanced numbers less than $10^n$.
							 
						 
					
						
							
								
									
										
										
										
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								Thus: $T(1) = 45$, $T(2) = 540$ and $T(5) = 334\\,795\\,890$.
							 
						 
					
						
							
								
									
										
										
										
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								Find $T(47)\\,mod\\,3^{15}$
							 
						 
					
						
							
								
									
										
										
										
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								# --hints--
  
						 
					
						
							
								
									
										
										
										
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								`balancedNumbers()`  should return `6273134` . 
						 
					
						
							
								
									
										
										
										
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								```js
							 
						 
					
						
							
								
									
										
										
										
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								assert.strictEqual(balancedNumbers(), 6273134);
							 
						 
					
						
							
								
									
										
										
										
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								```
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
									
										
										
										
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								# --seed--
  
						 
					
						
							
								
									
										
										
										
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								## --seed-contents--
  
						 
					
						
							
								
									
										
										
										
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								```js
							 
						 
					
						
							
								
									
										
										
										
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								function balancedNumbers() {
							 
						 
					
						
							
								
									
										
										
										
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								  return true;
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								}
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
									
										
										
										
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								balancedNumbers();
							 
						 
					
						
							
								
									
										
										
										
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								```
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								
							 
						 
					
						
							
								
									
										
										
										
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								# --solutions--
  
						 
					
						
							
								
									
										
										
										
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								```js
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								// solution required
							 
						 
					
						
							
								
							 
							
								
							 
							
								 
							
							
								```