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                2.320.940
tests have already been made here ?
Also try how good you are at mental arithmetic!
Arithmetic without time? Go to leren-rekenen.nl
Here you learn arithmetic error-free for FREE
                        
                        
Additions of  12-20
                In these additions you add two nummbers. One number is between 10 and 20 and the other number is between 2 and 20. The outcome is between 12 and 40.