Răspuns:
978 - 835 = 143
Proba: 143 + 835 = 978
1.020 - 835 = 185
proba : 185 + 835 = 1.020
2.309 - 835 = 1.474
Proba: 1.474 + 835 = 2.309
825 - 138 = 687
Proba : 687 + 138 = 825
785 - 687= 98
Proba : 785 - 98 = 687
687 + 98 =785
837 - 687 = 148
Proba : 150+ 687 = 837
