Mixing the Methods - Mental Exercises for the Day

Some Problem Sets

Record the problems on the board or modelling book in the horizontal form.

Set 1
45 + 58      67 + □ = 121     8 001 – 7 998     26 + □ = 52     81 – 67     
456 + 144    789 – 85          □ + 58 = 189      33 + 809 + 67 + 91
 

Set 2
28 + 72        191 + □ = 210        7 001 – 21       39 + □ = 77         234 – 99         
6091 + 109   2 782 – 15             □ + 123 = 149        616 + 407 – 16 + 93
 

Set 3
999 + 702         287 + □ = 400         2 067 – 999        45 + □ = 91      771 – 37 316 + 684         709 – 70                 □ + 88 = 200        7 898 – 6 000 – 98 – 100
 

Set 4
38 + 128           14 + □ = 101           9 000 – 8 985          102 – □ = 34    800 – 33 78 + 124        4 444 – 145                 □ + 8 = 1 003           4 700 – 498 + 200 –2
 

Set 5
405 + 58          880 + □ = 921         8 789 – 7 678         80 – □ = 41     701 – 96  8 888 + 122      781 – 45                  □ + 48 = 789          6 000 – 979 – 11 – 10