Răspuns:
4) a) 2 1 × 7 = 2×3 +1 × 7 = 7 × 7 =49
3 5 3 5 3 5 15
b) 5 × 1 10 = 5 × 1×13+10 = 5 × 23 = 115
9 13 9 13 9 13 117
c) 2 3 × 4 = 2×4+3 ×4 = 11 × 4 = 11
4 9 4 9 4 9 9
d) 4 2 × 2 = 4×3+2 × 2 = 14 × 2 = 28
3 5 3 5 3 5 15
e) 2 3 × 4 = 2×4+3 × 4 = 11 × 4 = 1
4 11 4 11 4 11
f) 2 7 × 9 = 2×3+7 ×9 = 13 × 9 = 39
3 2 3 2 3 2 2
g) 3 5 × 30 = 3×6+5 × 30 = 23 × 30 = 5
6 23 6 23 6 23
6) a) 2 1 × 7 × 6 = 2×4+1 ×7 ×6 = 9 ×7 ×6 =63
4 3 4 3 4 3 2
b) 7 × 1 3 × 4 = 7 × 1×5+3 ×4 = 7 × 8 × 4=28
8 5 8 5 8 5 5
c) 5 × 6 × 8 = 30 × 8 = 8
3 10 30
d) 9 × 2 1 × 5 =9 × 2×2+1 ×5 = 9 × 5 × 5 = 1
25 2 9 25 2 9 25 2 9 2
e) 1 13 × 5 × 2 2 = 15×1+13 × 5 × 2×7+2 =
15 8 7 15 8 7
= 28 × 5 × 16 = 4 × 1 × 2 = 8
15 8 7 3 1 1 3
