Ma’ruzalar matni

4. 37 - 20 ni hisoblash usulini toping	37 – 20 = (37 - 7) – 20 = (30 – 20) + 7 = -10 - 7 = 17;	37 – 20 = (30 + 7) – 20 = (30 – 20) + 7 = 10 + 7 = 17;	37 – 20 = (30 - 7) – 20 = (30 – 20) -7 = 10 + 7 = 17;
37 – 20 = (30 - 7) + 20 = (30 – 20) - 7 = -10 + 7 = 17;
5. 37 – 2 ni hisoblash usulini toping.	37 – 2 = (37 - 7) – 2 = 30 + (7 – 2) = -30 + 5 = 35;	37 – 2 = (30 + 7) – 2 = 30 + (7 – 2) = 30 + 5 = 35;	37 – 2 = (30 - 7) + 2 = 30 + (7 – 2) = -30 - 5 = 35;	37 – 2 = (30 + 7) – 2 = 30 - (7 – 2) = 30 - 5 = 35;
6. 25 + 17 ni hisoblash usulini toping.	25 + 17 = (22 + 3) + 17 = 22 + (3 + 17) = 22 + 20 = 42;	25 + 17 = (20 + 5) - (10 + 7) = (20 + 10) - (5 + 7) = 30 + 12 = 42;	25 + 17 = (20 + 5) + 10+7 = (20 + 17) - 5 = 37 + 5 = (37 + 3) + 2 = 42;	25 + 17 = 20+5 - (5 + 12) = (25 + 5) - 12 = 30 + 12 = 42;