Oblicz:
a) 81 x 30 b) 240 x 6 c) 40 x 50 d) 320 x 8
130 x 4 35 x 80 280 x 30 24 x 60
120 x 60 40 x 13 260 x 20 150 x 9
14 x 70 46 x 50 160 x 60 7 x 840
Odpowiedż:
a)
81 x 30 = (80 x 30) + (1 x 30) = 2400 + 30 = 2430
130 x 4 = (100 x 4) + (4 x 30) = 400 + 120 = 520
120 x 60 = (100 x 60) + ((60 x 20) = 6000 + 1200 = 7200
14 x 70 = (10 x 70) + (4 x 70) = 700 + 280 = 980
b)
240 x 6 = (200 x 6) + (40 x 6) = 1200 + 240 = 1440
35 x 80 = (30 x 80) + (5 x 80) = 2400 + 400 = 2800
40 x 13 = (40 x 10) + (40 x 3) = 400 + 120 = 520
46 x 50 = (40 x 50) + (6 x 50) = 2000 + 300 = 2300
c)
40 x 50 = 4 x 10 x 5 x 10 = 20 x 10 x 10 = 2000
280 x 30 = (200 x 30) + (80 x 30) = 6000 + 2400 = 8400
260 x 20 = 260 x 2 x 10 = 520 x 10 = 5200
160 x 60 = 160 x 6 x 10 = 960 x 10 = 9600
d)
320 x 8 = (8 x 300) +(8 x 20) = 2400 + 160 = 2560
24 x 60 = 24 x 6 x 10 = 144 x 10 = 1440
150 x 9 = (9 x 100) + (9 x 50) = 900 + 450 = 1350
7 x 840 = (7 x 800) + (7 x 40) = 5600 + 280 =5880
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