a, 61.49+27.49+12.49+100.51 = 49.(61+27+12)+100.51 = 49.100+51.100 = 100.(49+51) = 100.100 = 10000
b, 2 3 . 3 3 . 5 + 9 . 6 3 - 8 . 6 3 . 2018 0 (để kết quả dưới dạng lũy thừa)
= 6 3 . 5 + 6 3 . 9 - 8 . 6 3 . 1 = 6 3 . ( 5 + 9 - 8 ) = 6 4
c, 25.5.4.27.2 = (25.4).(5.2).27 = 100.10.27 = 27000
d, 12:{400:[500 – (125+25.7)]} = 12:{400:[500 – 300]} = 12:(400:200) = 12:2 = 6
e, 3 2 . 4 2 . 7 + 12 2 . 6 - 6 2 . 2 2 . 13 + 2020 0
= 12 2 . 7 + 12 2 . 6 - 12 2 . 3 + 1
= 12 2 . 7 + 6 - 13 + 1 = 1