Tính nhanh. a) 14 + 27 + 36 b) 4.15.25.6 c) 5.125.2.4 d) 176+483+24+117

* Hướng dẫn giải

a) 14 + 27 + 36 = (14 + 36) + 27 = 50 + 27 = 77

b) 4.15.25.6 = (4.25).(15.6) = 100.90 = 9000

c) 5.125.2.4 = (5.4).(125.4) = 10.500 = 5000

d) 176 + 483 + 24 + 117 = (176+24) + (483 + 117) = 200 + 600 = 800

e) 12.41 + 12.59 = 12.(41+59) = 12.100 = 1200

f) 17.32 + 43.17 + 17.25 = 17.(32+43+25) = 17.100 = 1700

g) 2 + 4 + 6 + … + 22 = 2.(1 + 2 + 3 + … + 11) = 2.(12.11:2) = 2.66 = 132