Activité 6 - Suppression de parenthèses

a) Calcule en notant ton procédé.
1000 – 102

= 1000 – (100 + 2)
= 1000 – 100 – 2
= 900 – 2
= 898


1000 – 120
= 1000 – (100 + 20)
= 1000 – 100 – 20
= 900 – 20
= 880

1000 – 95
= 1000 – (100 5)
= 1000 – 100 + 5
= 900 + 5
= 905

100 – 13
= 100 – (10 + 3)
= 100 – 10 – 3
= 90 – 3
= 87

100 – 39
= 100 – (40 – 1)
= 100 – 40 + 1
= 60 + 1
= 61

450 + 99
= 450 + (100 – 1)
= 450 + 100 – 1
= 550 – 1
= 549

250 + 195
= 250 + (200 – 5)
= 250 + 200 – 5
= 450 – 5
= 445

187 + 102
= 187 + (100 + 2)
= 187 + 100 + 2
= 287 + 2
= 289

288 + 394
= 288 + (400 – 6)
= 288 + 400 – 6
= 688 – 6
= 682

137 + 198
= 137 + (200 – 2)
= 137 + 200 – 2
= 337– 2
= 335