Oblicz w pamięci
a) 16 + 46 +24 b) 31 + 17 +29 c) 16 + 25 + 24 + 35
28 + 27 +22 63 +15 + 27 37 + 26 +23 + 14
71 + 99 + 11 33 + 35 + 37 27 + 23 + 18 +32
Odpowiedz:
a)
16 + 46 + 24 = (10 + 40 + 20) + (6 +6 + 4) = 70 + 16 = 86
28 + 27 + 22= ( 20 + 20 + 20) + (8 +7 +2) = 60 + 17 = 77
71 + 99 + 11= (70 + 90 + 10) + (1 +9 +1) = 170 +11 = 181
b)
31 + 17 + 29 = (30 + 10 +20) + (1 + 7 + 9) = 60 + 17 = 77
63 + 15 +27 = (60 +10 + 20) + (3 + 5 + 7) = 90 + 15 = 105
33 + 35 +37 = (30 + 30 +30) + (3 +5 +7) = 90 + 15 = 105
c)
16 + 25 + 24 + 35 = (10 + 20 + 20 + 30) + (6 + 5 + 4 +5) = 80 + 20 = 100
37 + 26 + 23 + 14 = (30 + 20 + 20 +10) + (7 + 6 + 3 + 4) = 80 + 20 = 100
27 + 23 + 18 + 32 = (20 + 20 + 10 + 30) + (7 + 3 +8 + 2) = 80 + 20 = 100
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