25,048
students have developed their Kotlin skills on Exercism.

Students
25,048
Submissions
75,031
Mentoring Discussions
5,124

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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
10,628
8,942 (avg. 0.8)
7,680 (72.3%)
13 (0.1%)
Two Fer Two Fer
5,705
6,895 (avg. 1.2)
4,453 (78.1%)
1,523 (26.7%)
Hamming Hamming
3,639
5,070 (avg. 1.4)
2,890 (79.4%)
804 (22.1%)
Gigasecond Gigasecond
2,695
3,333 (avg. 1.2)
2,155 (80.0%)
462 (17.1%)
Scrabble Score Scrabble Score
2,069
2,877 (avg. 1.4)
1,811 (87.5%)
371 (17.9%)
Matrix Matrix
1,206
1,434 (avg. 1.2)
899 (74.5%)
142 (11.8%)
Difference of Squares Difference of Squares
1,489
2,072 (avg. 1.4)
1,300 (87.3%)
239 (16.1%)
Secret Handshake Secret Handshake
1,233
1,587 (avg. 1.3)
971 (78.8%)
197 (16.0%)
Triangle Triangle
1,020
1,450 (avg. 1.4)
837 (82.1%)
161 (15.8%)
Saddle Points Saddle Points
725
862 (avg. 1.2)
513 (70.8%)
109 (15.0%)
Flatten Array Flatten Array
766
951 (avg. 1.2)
619 (80.8%)
84 (11.0%)
Word Count Word Count
739
954 (avg. 1.3)
581 (78.6%)
72 (9.7%)
Robot Name Robot Name
556
752 (avg. 1.4)
432 (77.7%)
71 (12.8%)
Rotational Cipher Rotational Cipher
396
517 (avg. 1.3)
335 (84.6%)
56 (14.1%)
Bank Account Bank Account
499
601 (avg. 1.2)
380 (76.2%)
62 (12.4%)
Linked List Linked List
423
500 (avg. 1.2)
319 (75.4%)
44 (10.4%)
Binary Search Binary Search
362
412 (avg. 1.1)
280 (77.3%)
39 (10.8%)
Pangram Pangram
2,321
2,902 (avg. 1.3)
1,823 (78.5%)
92 (4.0%)
Raindrops Raindrops
1,518
1,866 (avg. 1.2)
1,234 (81.3%)
66 (4.3%)
Isogram Isogram
1,051
1,290 (avg. 1.2)
854 (81.3%)
51 (4.9%)
Pig Latin Pig Latin
775
692 (avg. 0.9)
449 (57.9%)
23 (3.0%)
Anagram Anagram
830
932 (avg. 1.1)
612 (73.7%)
35 (4.2%)
Resistor Color Resistor Color
890
986 (avg. 1.1)
740 (83.1%)
12 (1.3%)
Resistor Color Duo Resistor Color Duo
786
939 (avg. 1.2)
646 (82.2%)
8 (1.0%)
RNA Transcription RNA Transcription
1,897
2,318 (avg. 1.2)
1,628 (85.8%)
67 (3.5%)
Diamond Diamond
613
700 (avg. 1.1)
428 (69.8%)
21 (3.4%)
Bob Bob
546
607 (avg. 1.1)
417 (76.4%)
15 (2.7%)
Beer Song Beer Song
455
480 (avg. 1.1)
334 (73.4%)
17 (3.7%)
Acronym Acronym
1,069
1,287 (avg. 1.2)
900 (84.2%)
23 (2.2%)
Armstrong Numbers Armstrong Numbers
298
342 (avg. 1.1)
253 (84.9%)
5 (1.7%)
Resistor Color Trio Resistor Color Trio
605
676 (avg. 1.1)
436 (72.1%)
5 (0.8%)
Transpose Transpose
542
481 (avg. 0.9)
287 (53.0%)
4 (0.7%)
ISBN Verifier ISBN Verifier
311
333 (avg. 1.1)
228 (73.3%)
4 (1.3%)
Largest Series Product Largest Series Product
590
797 (avg. 1.4)
447 (75.8%)
11 (1.9%)
Luhn Luhn
700
833 (avg. 1.2)
515 (73.6%)
12 (1.7%)
Nucleotide Count Nucleotide Count
414
496 (avg. 1.2)
328 (79.2%)
11 (2.7%)
Phone Number Phone Number
411
476 (avg. 1.2)
320 (77.9%)
8 (1.9%)
Series Series
323
363 (avg. 1.1)
260 (80.5%)
8 (2.5%)
Roman Numerals Roman Numerals
349
354 (avg. 1.0)
250 (71.6%)
8 (2.3%)
Leap Leap
1,174
1,323 (avg. 1.1)
891 (75.9%)
36 (3.1%)
Custom Set Custom Set
361
349 (avg. 1.0)
237 (65.7%)
4 (1.1%)
Space Age Space Age
893
1,105 (avg. 1.2)
739 (82.8%)
15 (1.7%)
Allergies Allergies
353
401 (avg. 1.1)
257 (72.8%)
3 (0.8%)
Meetup Meetup
211
182 (avg. 0.9)
128 (60.7%)
0 (0.0%)
Crypto Square Crypto Square
225
224 (avg. 1.0)
137 (60.9%)
2 (0.9%)
Run-Length Encoding Run-Length Encoding
288
305 (avg. 1.1)
196 (68.1%)
3 (1.0%)
Scale Generator Scale Generator
207
159 (avg. 0.8)
111 (53.6%)
0 (0.0%)
Wordy Wordy
224
230 (avg. 1.0)
132 (58.9%)
4 (1.8%)
Minesweeper Minesweeper
286
264 (avg. 0.9)
170 (59.4%)
4 (1.4%)
Dominoes Dominoes
117
89 (avg. 0.8)
53 (45.3%)
2 (1.7%)
Perfect Numbers Perfect Numbers
543
711 (avg. 1.3)
452 (83.2%)
11 (2.0%)
Yacht Yacht
184
200 (avg. 1.1)
137 (74.5%)
1 (0.5%)
Sieve Sieve
387
465 (avg. 1.2)
303 (78.3%)
3 (0.8%)
Sum of Multiples Sum of Multiples
588
677 (avg. 1.2)
438 (74.5%)
7 (1.2%)
Forth Forth
183
158 (avg. 0.9)
95 (51.9%)
6 (3.3%)
Grains Grains
404
515 (avg. 1.3)
321 (79.5%)
6 (1.5%)
Robot Simulator Robot Simulator
196
222 (avg. 1.1)
132 (67.3%)
2 (1.0%)
Collatz Conjecture Collatz Conjecture
364
432 (avg. 1.2)
291 (79.9%)
9 (2.5%)
Kindergarten Garden Kindergarten Garden
130
136 (avg. 1.0)
92 (70.8%)
1 (0.8%)
Nth Prime Nth Prime
331
384 (avg. 1.2)
257 (77.6%)
4 (1.2%)
Pascal's Triangle Pascal's Triangle
196
203 (avg. 1.0)
144 (73.5%)
1 (0.5%)
Prime Factors Prime Factors
184
181 (avg. 1.0)
127 (69.0%)
0 (0.0%)
Complex Numbers Complex Numbers
206
194 (avg. 0.9)
129 (62.6%)
5 (2.4%)
All Your Base All Your Base
160
163 (avg. 1.0)
104 (65.0%)
0 (0.0%)
Clock Clock
159
176 (avg. 1.1)
108 (67.9%)
0 (0.0%)
Matching Brackets Matching Brackets
212
227 (avg. 1.1)
154 (72.6%)
4 (1.9%)
Spiral Matrix Spiral Matrix
195
184 (avg. 0.9)
128 (65.6%)
1 (0.5%)
Change Change
267
212 (avg. 0.8)
118 (44.2%)
8 (3.0%)
Binary Search Tree Binary Search Tree
108
89 (avg. 0.8)
60 (55.6%)
0 (0.0%)
ETL ETL
274
322 (avg. 1.2)
224 (81.8%)
4 (1.5%)
Grade School Grade School
198
217 (avg. 1.1)
144 (72.7%)
5 (2.5%)
Affine Cipher Affine Cipher
95
101 (avg. 1.1)
59 (62.1%)
0 (0.0%)
Atbash Cipher Atbash Cipher
308
393 (avg. 1.3)
247 (80.2%)
2 (0.6%)
Rail Fence Cipher Rail Fence Cipher
157
134 (avg. 0.9)
88 (56.1%)
1 (0.6%)
Say Say
133
124 (avg. 0.9)
80 (60.2%)
1 (0.8%)
Simple Cipher Simple Cipher
177
160 (avg. 0.9)
99 (55.9%)
0 (0.0%)
Sublist Sublist
153
136 (avg. 0.9)
95 (62.1%)
0 (0.0%)
Diffie-Hellman Diffie-Hellman
121
103 (avg. 0.9)
68 (56.2%)
1 (0.8%)
List Ops List Ops
224
170 (avg. 0.8)
113 (50.4%)
1 (0.4%)
Zebra Puzzle Zebra Puzzle
114
74 (avg. 0.6)
38 (33.3%)
1 (0.9%)
React React
233
171 (avg. 0.7)
92 (39.5%)
4 (1.7%)
D&D Character D&D Character
915
945 (avg. 1.0)
563 (61.5%)
10 (1.1%)
Reverse String Reverse String
1,768
1,695 (avg. 1.0)
1,271 (71.9%)
15 (0.8%)
Darts Darts
438
501 (avg. 1.1)
323 (73.7%)
3 (0.7%)
Knapsack Knapsack
46
38 (avg. 0.8)
24 (52.2%)
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