Question

Grupaţi termenii, apoi efectuați rapid adunările, după model: Model: 4+3+7+16=(4+16)+(3+7)=20+10=30. 3+17+3+27; 1+29+4+3; 18+ 12 +5+5; 2+8+3+6+4+7; 11+12+19+28; 7+9+13 +21; 40 21+13+9+7; 32+8+4+16; 23 +7+9+41.​

Answer 1

1. (3+17)+(3+27)=20+30=50
2. (1+29)+(4+3)=30+7=37
3. (18+12)+(5+5)=30+10=40
4. (2+8)+(3+7)+(6+4)=10+10+10=30
5. (11+19)+(12+28)=30+40=70
6. (7+13)+(9+21)=20+30=50
7. (32+8)+(16+4)=40+20=60
8. (23+7)+(41+9)=30+50=80