Zadanie 17,strona 52.Szkoła podstawowa,klasa 4 (podręcznik)

Oblicz sprytnie, np 85 – 28 – 37 = 85 – (28 + 37) = 85 – 65 = 20

a) 72 – 14 -28             b) 92 – 26 – 44             c) 75 – (15 + 29)

90 – 33 – 27                    83 – 27 – 36                 85 – (35 + 18)

102 – 21 – 21                  67 – 24 – 16                 88 – (18 + 28)

 

Odpowiedż:

a)

72 – 14 -28 = 72 – (14 + 28) = 72 – 42 = 30

90 – 33 – 27 = 90 – (33 + 27) = 90 – 60 = 30

102 – 21 – 21 = 102 – (21 + 21) = 102 – 42 = 60

b)

92 – 26 – 44 = 92 – (26 + 44) = 92 – 70 = 22

83 – 27 – 36 = 83 – (27 + 36) = 83 – 63 = 20

67 – 24 – 16 = 67 – (24 + 16) = 67 – 40 = 27

c)

75 – (15 + 29) = 75 – 15 – 29 = 60 – 29 = 31

85 – (35 + 18) = 85 – 35 – 18 = 50 – 18 = 32

88 – (18 + 28) = 88 – 18 – 28 = 70 – 28 = 42