Addition
This is the most important calculation and takes the lionâ€™s share of the whole calculation section. Addition is also treated as the building block for all the other calculations like subtraction, multiplication etc.
Unfortunately, we donâ€™t have any scut for additions. The only thing that can be done is, practice.
I would suggest a 4 x 4 table for this practice:
Unfortunately, we donâ€™t have any scut for additions. The only thing that can be done is, practice.
I would suggest a 4 x 4 table for this practice:

Column 1 
Column 2 
Column 3 
Column 4 
Row 1 




Row 2 




Row 3 




Row 4 




Fill in this table with two digit numbers and add all the columns and rows. To obtain a faster speed, it is advisable that both the digits are added simultaneously. For this, we need to train our mind to retain both the digits of a number simultaneously and then add it in one go with the two digits of the other number.
I would suggest, that rather than adding the unit digit first, add the tens place digit first; and while your brain is adding the tens place digit, your eyes should have captured the unit digit.
Sample table:

Column 1

Column 2

Column 3

Column 4


Row 1

36

42

67

98

243

Row 2

46

54

28

72

200

Row 3

58

45

82

89

274

Row 4

49

58

36

92

235


189

199

213

351


Rate your calculation speed:
The above given time includes time for writing the sum and it does not consider the time taken for creating the table and putting values inside it.
The idea is that if, 3 + 4 = 7 can be done without any effort (ask yourself after doing the addition if did you put any effort), then we could be in a position to do 79 + 68 = 147 also without any effort. And with this practice exercise, we want to achieve the same.
Subtraction
Once we attain a good speed in addition, subtraction too will become fast as a natural outcome.