1. 90×(27+33-53) = 90×7= 630
(904-687)×80= 217×80 = 17.360
87-27×(28-19)= 60×9 = 540
704×37= 28.048
809×40= 32.360
390×60= 23.400
2. a) 9×8×10= 720
9+8+10= 27
720-27= 693
b) 50-4-2= 44
50×4×2= 400
400+44= 444
c) 683-317= 366
683+317= 1.000
1.000×366= 366.000
3. 30×6×100= 18.000
40×7×10= 2.800
25×5×2= 250
35×2×5+350= 700
41×11-41×10= 41
4. 278×49= 13.622
794×56= 44.464
189×98= 18.522
365×68= 24.820
473×27= 12.771
546×74= 40.404
5. 3+8-4+3+9-5 = 14
6. a) 360+5×3+5×125= 1.000
b) (35+15)×9-250= 50×9-250 = 200
c) 6×(237+118-119-36)= 6×200= 1.200
