Tính nhanh:
a) 2.31.12 + 4.6.42 + 8.27.3
b) 36.28 + 36.82 + 64a.69 + 64.41
a) 2.31.12 + 4.6.42 + 8.27.3 = 24.31 = 24.42 + 24.27
= 24. ( 31 + 42 + 27) = 24.100 = 2400
b) 36.28 + 36.82 + 64.69 + 64.41 = 36.(28 + 82) + 64.(69 + 41)
= 36.110 + 64.110 = 110.( 36 + 64 ) =110 .110 = 11000
-- Mod Toán 6