22,133
students have developed their Kotlin skills on Exercism.

Students
22,133
Submissions
69,671
Mentoring Discussions
5,064

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Practice Exercises are exercises designed to allow students to solve an arbitrary problem, with the aim of them making use of the concepts they have learned so far.

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Usage statistics

85 active practice exercises
Started
Attempts
Completions
Mentoring requests
Hello World Hello World
9,543
8,115 (avg. 0.9)
6,928 (72.6%)
13 (0.1%)
Two Fer Two Fer
5,175
6,315 (avg. 1.2)
4,016 (77.6%)
1,510 (29.2%)
Hamming Hamming
3,236
4,610 (avg. 1.4)
2,585 (79.9%)
794 (24.5%)
Gigasecond Gigasecond
2,405
2,998 (avg. 1.2)
1,926 (80.1%)
452 (18.8%)
Scrabble Score Scrabble Score
1,843
2,609 (avg. 1.4)
1,612 (87.5%)
367 (19.9%)
Matrix Matrix
1,002
1,197 (avg. 1.2)
737 (73.6%)
137 (13.7%)
Difference of Squares Difference of Squares
1,326
1,842 (avg. 1.4)
1,150 (86.7%)
233 (17.6%)
Secret Handshake Secret Handshake
1,096
1,431 (avg. 1.3)
859 (78.4%)
194 (17.7%)
Triangle Triangle
914
1,317 (avg. 1.4)
744 (81.4%)
158 (17.3%)
Saddle Points Saddle Points
642
770 (avg. 1.2)
460 (71.7%)
107 (16.7%)
Flatten Array Flatten Array
644
842 (avg. 1.3)
533 (82.8%)
84 (13.0%)
Word Count Word Count
639
839 (avg. 1.3)
512 (80.1%)
71 (11.1%)
Robot Name Robot Name
492
675 (avg. 1.4)
391 (79.5%)
69 (14.0%)
Rotational Cipher Rotational Cipher
349
457 (avg. 1.3)
297 (85.1%)
56 (16.0%)
Bank Account Bank Account
406
505 (avg. 1.2)
315 (77.6%)
61 (15.0%)
Linked List Linked List
378
450 (avg. 1.2)
286 (75.7%)
44 (11.6%)
Binary Search Binary Search
326
376 (avg. 1.2)
253 (77.6%)
39 (12.0%)
Pangram Pangram
2,260
2,827 (avg. 1.3)
1,766 (78.1%)
92 (4.1%)
Raindrops Raindrops
1,469
1,801 (avg. 1.2)
1,187 (80.8%)
64 (4.4%)
Isogram Isogram
1,015
1,247 (avg. 1.2)
823 (81.1%)
51 (5.0%)
Pig Latin Pig Latin
749
669 (avg. 0.9)
431 (57.5%)
23 (3.1%)
Anagram Anagram
795
897 (avg. 1.1)
582 (73.2%)
35 (4.4%)
Resistor Color Resistor Color
847
934 (avg. 1.1)
699 (82.5%)
12 (1.4%)
Resistor Color Duo Resistor Color Duo
739
872 (avg. 1.2)
604 (81.7%)
8 (1.1%)
RNA Transcription RNA Transcription
1,853
2,270 (avg. 1.2)
1,588 (85.7%)
67 (3.6%)
Diamond Diamond
589
673 (avg. 1.1)
410 (69.6%)
21 (3.6%)
Bob Bob
516
577 (avg. 1.1)
396 (76.7%)
15 (2.9%)
Beer Song Beer Song
429
455 (avg. 1.1)
316 (73.7%)
17 (4.0%)
Acronym Acronym
1,025
1,220 (avg. 1.2)
862 (84.1%)
23 (2.2%)
Armstrong Numbers Armstrong Numbers
261
293 (avg. 1.1)
220 (84.3%)
5 (1.9%)
Resistor Color Trio Resistor Color Trio
576
632 (avg. 1.1)
409 (71.0%)
5 (0.9%)
Transpose Transpose
508
453 (avg. 0.9)
266 (52.4%)
4 (0.8%)
ISBN Verifier ISBN Verifier
285
302 (avg. 1.1)
208 (73.0%)
4 (1.4%)
Largest Series Product Largest Series Product
567
775 (avg. 1.4)
431 (76.0%)
11 (1.9%)
Luhn Luhn
672
807 (avg. 1.2)
492 (73.2%)
12 (1.8%)
Nucleotide Count Nucleotide Count
389
466 (avg. 1.2)
310 (79.7%)
11 (2.8%)
Phone Number Phone Number
386
448 (avg. 1.2)
300 (77.7%)
8 (2.1%)
Series Series
301
340 (avg. 1.1)
242 (80.4%)
8 (2.7%)
Roman Numerals Roman Numerals
326
328 (avg. 1.0)
234 (71.8%)
7 (2.1%)
Leap Leap
1,139
1,285 (avg. 1.1)
859 (75.4%)
36 (3.2%)
Custom Set Custom Set
334
323 (avg. 1.0)
217 (65.0%)
3 (0.9%)
Space Age Space Age
869
1,081 (avg. 1.2)
719 (82.7%)
15 (1.7%)
Allergies Allergies
331
379 (avg. 1.1)
243 (73.4%)
3 (0.9%)
Meetup Meetup
200
169 (avg. 0.8)
120 (60.0%)
0 (0.0%)
Crypto Square Crypto Square
207
204 (avg. 1.0)
124 (59.9%)
1 (0.5%)
Run-Length Encoding Run-Length Encoding
269
282 (avg. 1.0)
181 (67.3%)
2 (0.7%)
Scale Generator Scale Generator
191
148 (avg. 0.8)
102 (53.4%)
0 (0.0%)
Wordy Wordy
211
216 (avg. 1.0)
126 (59.7%)
4 (1.9%)
Minesweeper Minesweeper
245
232 (avg. 0.9)
148 (60.4%)
4 (1.6%)
Dominoes Dominoes
108
86 (avg. 0.8)
51 (47.2%)
2 (1.9%)
Perfect Numbers Perfect Numbers
528
697 (avg. 1.3)
441 (83.5%)
11 (2.1%)
Yacht Yacht
168
181 (avg. 1.1)
123 (73.2%)
1 (0.6%)
Sieve Sieve
378
455 (avg. 1.2)
297 (78.6%)
3 (0.8%)
Sum of Multiples Sum of Multiples
574
660 (avg. 1.1)
427 (74.4%)
7 (1.2%)
Forth Forth
151
143 (avg. 0.9)
84 (55.6%)
6 (4.0%)
Grains Grains
396
507 (avg. 1.3)
317 (80.1%)
6 (1.5%)
Robot Simulator Robot Simulator
187
217 (avg. 1.2)
128 (68.4%)
2 (1.1%)
Collatz Conjecture Collatz Conjecture
351
419 (avg. 1.2)
282 (80.3%)
8 (2.3%)
Kindergarten Garden Kindergarten Garden
124
133 (avg. 1.1)
90 (72.6%)
1 (0.8%)
Nth Prime Nth Prime
322
375 (avg. 1.2)
251 (78.0%)
4 (1.2%)
Pascal's Triangle Pascal's Triangle
188
197 (avg. 1.0)
140 (74.5%)
1 (0.5%)
Prime Factors Prime Factors
178
175 (avg. 1.0)
124 (69.7%)
0 (0.0%)
Complex Numbers Complex Numbers
193
184 (avg. 1.0)
123 (63.7%)
4 (2.1%)
All Your Base All Your Base
155
157 (avg. 1.0)
101 (65.2%)
0 (0.0%)
Clock Clock
148
167 (avg. 1.1)
103 (69.6%)
0 (0.0%)
Matching Brackets Matching Brackets
203
217 (avg. 1.1)
149 (73.4%)
4 (2.0%)
Spiral Matrix Spiral Matrix
189
178 (avg. 0.9)
126 (66.7%)
1 (0.5%)
Change Change
242
193 (avg. 0.8)
107 (44.2%)
7 (2.9%)
Binary Search Tree Binary Search Tree
98
82 (avg. 0.8)
57 (58.2%)
0 (0.0%)
ETL ETL
267
314 (avg. 1.2)
220 (82.4%)
4 (1.5%)
Grade School Grade School
189
210 (avg. 1.1)
141 (74.6%)
5 (2.6%)
Affine Cipher Affine Cipher
88
97 (avg. 1.1)
56 (63.6%)
0 (0.0%)
Atbash Cipher Atbash Cipher
303
390 (avg. 1.3)
245 (80.9%)
2 (0.7%)
Rail Fence Cipher Rail Fence Cipher
152
130 (avg. 0.9)
86 (56.6%)
1 (0.7%)
Say Say
126
119 (avg. 0.9)
77 (61.1%)
1 (0.8%)
Simple Cipher Simple Cipher
165
151 (avg. 0.9)
94 (57.0%)
0 (0.0%)
Sublist Sublist
142
125 (avg. 0.9)
87 (61.3%)
0 (0.0%)
Diffie-Hellman Diffie-Hellman
104
88 (avg. 0.8)
58 (55.8%)
1 (1.0%)
List Ops List Ops
186
148 (avg. 0.8)
97 (52.2%)
1 (0.5%)
Zebra Puzzle Zebra Puzzle
99
64 (avg. 0.6)
33 (33.3%)
1 (1.0%)
React React
182
137 (avg. 0.8)
73 (40.1%)
3 (1.6%)
D&D Character D&D Character
895
923 (avg. 1.0)
547 (61.1%)
10 (1.1%)
Reverse String Reverse String
1,741
1,669 (avg. 1.0)
1,246 (71.6%)
15 (0.9%)
Darts Darts
415
472 (avg. 1.1)
303 (73.0%)
3 (0.7%)
Knapsack Knapsack
39
30 (avg. 0.8)
19 (48.7%)
0 (0.0%)
4 deprecated practice exercises
Started
Attempts
Completions
Mentoring requests
Accumulate Accumulate
86
117 (avg. 1.4)
83 (96.5%)
7 (8.1%)
Binary Binary
34
46 (avg. 1.4)
32 (94.1%)
0 (0.0%)
Hexadecimal Hexadecimal
26
29 (avg. 1.1)
25 (96.2%)
1 (3.8%)
Strain Strain
28
36 (avg. 1.3)
27 (96.4%)
0 (0.0%)
44 unimplemented practice exercises
Alphametics Alphametics
Book Store Book Store
Bottle Song Bottle Song
Bowling Bowling
Circular Buffer Circular Buffer
Connect Connect
DOT DSL DOT DSL
Error Handling Error Handling
Food Chain Food Chain
Go Counting Go Counting
Grep Grep
Hangman Hangman
High Scores High Scores
House House
Killer Sudoku Helper Killer Sudoku Helper
Ledger Ledger
Lens Person Lens Person
Markdown Markdown
Micro Blog Micro Blog
OCR Numbers OCR Numbers
POV POV
PaaS I/O PaaS I/O
Palindrome Products Palindrome Products
Parallel Letter Frequency Parallel Letter Frequency
Poker Poker
Protein Translation Protein Translation
Proverb Proverb
Pythagorean Triplet Pythagorean Triplet
Queen Attack Queen Attack
REST API REST API
Rational Numbers Rational Numbers
Rectangles Rectangles
SGF Parsing SGF Parsing
Satellite Satellite
Simple Linked List Simple Linked List
Square Root Square Root
State of Tic-Tac-Toe State of Tic-Tac-Toe
Tournament Tournament
Tree Building Tree Building
Twelve Days Twelve Days
Two Bucket Two Bucket
Variable Length Quantity Variable Length Quantity
Word Search Word Search
Zipper Zipper