Here is the full list of all 63 Numbers & Letters achievements.
Started practice mode
Started practice mode 10 times
Successfully solved 10 equations in practice mode
Solved 20 equations in one game session in survival mode baby difficulty
Solved 20 equations in one game session in survival mode easy difficulty
Solved 20 equations in one game session in survival mode medium difficulty
Successfully solved 20 equations in survival mode hard difficulty
Successfully solved 12 equations in one game session in time trial mode baby difficulty
Successfully solved 12 equations in one game session in time trial mode easy difficulty
Successfully solved 12 equations in one game session in time trial mode medium difficulty
Successfully solved 12 equations in one game session in time trial mode hard difficulty
Successfully solved 12 equations in one game session in arcade mode baby difficulty
Successfully solved 12 equations in one game session in arcade mode easy difficulty
Successfully solved 12 equations in one game session in arcade mode medium difficulty
Successfully solved 12 equations in one game session in arcade mode hard difficulty
Successfully solved 12 letter puzzles in one game session and completed level in arcade mode in under 4 minutes
Successfully solved 15 letter puzzles in one game session in 5 minutes
Successfully solved 20 letter puzzles in one game session in 5 minutes
Successfully solved 25 letter puzzles in one game session in survival mode
Successfully solved 50 letter puzzles in one game session in survival mode
Successfully earned all survival mode difficulty achievements
Successfully earned all time trial mode difficulty achievements
Successfully earned all Arcade mode difficulty achievements
Successfully achieved the master rank in arcade, time trial and survival modes
Successfully solved 12 equations in one game session and fully completed level in arcade mode baby difficulty in under 3 minutes
Successfully solved 12 equations in one game session and completed level in arcade mode easy difficulty in under 5 minutes
Successfully solved 12 equations in one game session and completed level in arcade mode medium difficulty in under 8 minutes
Successfully solved 12 equations in one game session and completed level in arcade mode hard difficulty in under 10 minutes
Successfully earned all arcade time achievements
Successfully solved 20 equations in one game session in time trial hard difficulty
Solved 10 equations in one game session in Sudden Death
Solved 25 equations in one game session in Sudden Death
Solved 75 equations in one game session in Sudden Death
Completed level in arcade easy difficulty in under 1 minute
Completed level in arcade medium difficulty in under 1 minute
Completed level in arcade hard difficulty in under 1 minute
Solved 25 equations in one game session in Time Trial
Solved 35 equations in one game session in Time Trial
Solved 45 equations in one game session in Time Trial
Achieve a score of 10 in the Numbers Archery Time Trial Baby Mode
Achieve a score of 11 in the Numbers Archery Time Trial Easy Mode
Achieve a score of 13 in the Numbers Archery Time Trial Normal Mode
Achieve a score of 15 in the Numbers Archery Time Trial Hard Mode
Complete all achievements in the Numbers Archery Time Trial Mode
Survive 15 Equations in the Numbers Archery Survival Baby Mode
Survive 17 Equations in the Numbers Archery Survival Easy Mode
Survive 20 Equations in the Numbers Archery Survival Normal Mode
Survive 23 Equations in the Numbers Archery Survival Hard Mode
Complete all achievements in the Numbers Archery Survival Mode
Beat the Numbers Archery Arcade Baby Mode in under 2 minutes 45 seconds
Beat the Numbers Archery Arcade Easy Mode in under 3 minutes
Beat the Numbers Archery Arcade Normal Mode in under 3 minutes 30 seconds
Beat the Numbers Archery Arcade Hard Mode in under 4 minutes
Complete all achievements in the Numbers Archery Arcade Mode
Complete all Numbers Archery Mode Achievements
Reach a total of sum total of 1000 in numbers
Reach a total of sum total of 10000 in numbers
Reach a total of sum total of 50000 in numbers
Whack a total of 100 numbers
Whack a total of 1000 numbers
Whack a total of 5000 numbers
Reach a total of 75000 accumulated smashed numbers and Whack a total of 7500 Numbers