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gịgejyiywf ưkrfgjhqlihekjfgkjqefkueqvhqegoqieuvioqyelqkuee,jfblqfbbfhfhhhfdjqkfklakakuegkdlky37r0793ywlgb,fmaiydwgluyrq838yrgfj3

a) (20×5)×3246

=100×3246

b) 346×(53+47)

=346×100

= 34600

1/2 tấn < 400 yến

2/5 m2 > 3000 cm2 7/12 giờ > 40 phút

1/4 km < 250 m

a) 7/24 + 13/6 = 7/24 + 52/24 =7+52/24 = 9/24 b) 12/49 - 1/7 = 12/49 - 7/49 = 12-7/49 = 10/49 c) 5/8 × 24/25 = 5×24/8×25 = 120/200 d) 38/21 ÷ 19/3 = 38/21×3/19 = 114 /57

a) 2228655 b)13265