The Difficulty Level for sums in Stage-4 Workbook is pretty good. Only those students who have been sincere with Regular Abacus Practice till Stage-3 completion, will be able to do well with this level of Difficulty. Others will have to give up.
 
Addition & Subtraction sums get even more challenging with focus now shifting to maintaining good Accuracy in these larger sums. This will automatically help build good level of Concentration, along with other mental abilities. 
 
Visual sums for Addition & Subtraction also increase in size a bit. This is just to help push the student's mental abilities a little bit further up. The ability to do these sums Visually might be possible only for students who are under 13 years of age & have been sincere with Regular Abacus Practice right from the start.
 
Multiplication sums also move up in Stage-4, with 2-digit x 2-digit Abacus calculations being introduced. Along with that, students are supposed to start with 2-digit x 1-digit visual calculations. Remember that this ability to do Visual Calculations will be possible only for those students who have been Sincere with Abacus Practice right from the start.
 
Size of the Division sums also goes higher and now we introduce sums where there could be Remainders. Until Stage-3, all Division sums involved Dividends which were exactly divisible by the Divisors.
 
Stage-4 PDF file will need 32 sheets of A4 size for Printing (single side printing in Landscape mode). It contains over 2500 practice sums in all.
 
The Answer Key has been provided to make it very convenient to check the accuracy of the answers after solving the sums. This will save a lot of time for the Parent/Teacher & also help improve Accuracy for the student by correcting the mistakes in time.