Question

Calculați, după modelul prezentat:

12 ⋅ 99 = 12 ⋅ (100 – 1) = 12 ⋅ 100 – 12 ⋅ 1 = 1 200 – 12 = 1 188;

a) 35 ⋅ 99;
d) 31 ⋅ 98;

b) 27 ⋅ 101;
e) 4 ⋅ 999;

c) 15 ⋅ 102;
f) 5 ⋅ 1 004;
repede va rog frumos.​

Answer 1

a) 35 ∙ 99 = 35 ∙(100−1) = 35 ∙ 100 − 35 ∙ 1 = 3500 − 35 = 3465

b) 27 ∙ 101 = 27 ∙(100+1) = 27 ∙100 + 27 ∙ 1 = 2700 + 27 = 2727

c) 15 ∙ 102 = 15 ∙(100+2) = 15 ∙ 100 − 15 ∙ 2 = 1500 − 30 = 1530

d) 31 ∙ 98 = 31 ∙(100−2) = 31 ∙ 100 − 31 ∙ 2 = 3100 − 62 = 3038

e) 4 ∙ 999 = 4 ∙(1000−1) = 4 ∙ 1000 − 4 ∙ 1 = 4000 − 4 = 3996

f) 5 ∙ 1004 = 35 ∙(1000+4) = 5 ∙ 1000 + 5 ∙ 4 = 5000 + 20 = 5020