aduna numerele in doua moduri a) in ordinea in care sunt scrise b) schimband ordinea numerelor pentru a afla mai rapis rezultatul. 13+19 19+13 21+39 39+21 1+2+3+4+5+6 11+12+13+14+15+16 42+13+18+37 53+47+17+3 45+13+25+37 31+29+20+10 14+19+26+11 24+27+16+33
Răspunsuri la întrebare
13 + 19 = 19 + 13 = 32 → comutativitatea adunarii
21 + 39 = 60
39 + 21 = 60
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a)
1 + 2 + 3 + 4 + 5 + 6 = 21
= 3 + 3 + 4 + 5 + 6 =
= 10 + 5 + 6 =
= 15 + 6 =
= 21
b)
1 + 2 + 3 + 4 + 5 + 6 =
= ( 4 + 6 ) + ( 2 + 3 + 5 ) + 1 = → asociativitate
= 10 + 10 + 1 =
= 21
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a)
11 + 12 + 13 + 14 + 15 + 16 = 81
= 36 + 14 + 15 + 16 =
= 50 + 15 + 16 =
= 65 + 16 =
= 81
b)
11 + 12 + 13 + 14 + 15 + 16 = 81
= ( 14 + 16 ) + ( 12 + 13 + 15 ) + 11 =
= 30 + 40 + 11 =
= 81
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a)
42 + 13 + 18 + 37 = 55 + 18 + 37 = 73 + 37 = 110
b)
42 + 13 + 18 + 37 = ( 42 + 18 ) + ( 13 + 37 ) = 60 + 50 = 110
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a) 53 + 47 + 17 + 3 = 100 + 17 + 3 = 117 + 3 = 120
b) 53 + 47 + 17 + 3 = ( 53 + 47 ) + ( 17 + 3 ) = 100 + 20 = 120
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a) 45 + 13 + 25 + 37 = 58 + 25 + 37 = 83 + 37 = 120
b) 45 + 13 + 25 + 37 = ( 45 + 25 ) + ( 13 + 37 ) = 70 + 50 = 120
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a) 31 + 29 + 20 + 10 = 60 + 20 + 10 = 80 + 10 = 90
b) 31 + 29 + 20 + 10 = ( 31 + 29 ) + ( 20 + 10 ) = 60 + 30 = 90
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a) 14 + 19 + 26 + 11 = 33 + 26 + 11 = 59 + 11 = 70
b) 14 + 19 + 26 + 11 = ( 14 + 26 ) + ( 19 + 11 ) = 40 + 30 = 70
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a) 24 + 27 + 16 + 33 = 51 + 16 + 33 = 67 + 33 = 100
b) 24 + 27 + 16 + 33 = ( 24 + 16 ) + ( 27 + 33 ) = 40 + 60 = 100