CÁLCULO MENTAL...

7 + 8 + 3 = ...
( 7 + 3 + 8 )

5 + 9 – 7 = ...
[ (9 – 7) + 5 ]

9 – 3 + 5 = ...
( 5 – 3 + 9 )

7 – 2 – 4 = ...
[ 7 – (2+4) ]

27 + 35 = ...
( 27+3 + 35–3 )

76 – 29 = ...
( 76 – 30 + 1 )

2.357 + 694 = ...
( 2.357 + 700 – 6 )

2.357 – 694 = ...
( 2.357 – 700 + 6 )

29 x 2 = ...
(29 + 29)

37 x 3 = ...
(37 + 37 + 37)

37 x 4 = ...
( 37 x 2 x 2 )

28 x 5 = ...
( 28 / 2 x 10 )

43 x 6 = ...
( 43 x 3 x 2 )

23 x 7 = ...
( 23x5 + 23x2 )

52 x 8 = ...
( 52 x 2 x 2 x 2 )

37 x 9 = ...
( 37 x 10 – 37 )

73 x 11 = ...
( 73 x 10 + 73 )

64 x 12 = ...
( 64x10 + 64x2 )

87 x 15 = ...
( 87x10 + 87x10/2 )

76 / 5 = ...
( 76/10 x 2 )