數學(fast,easy)

52.7 x 1.95
= 50(1 + 0.95) + 2(1 + 0.95) + 0.7(1 + 0.95)
= 50 + 47.5 + 2 + 1.9 + 0.7 + 0.665
= 102.765

52.7*1.95
=52.7*(2-0.05)
=102.765

52.7 X 1.95
=52.7 X (2 - 0.05)
=52.7 X (2 - 0.1 / 2)
=52.7 X 2 - 52.7 X 0.1 / 2
=(53 - 0.3) X 2 - (53 - 0.3) X 0.1 / 2
= 53 X 2 - 0.3 X 2 - (53 X 0.1 / 2 - 0.3 X 0.1 / 2)
=(50 + 3) X 2 - 0.6 - (5.3 / 2 - 0.03 / 2)
=50 X 2 + 3 X 2 - 0.6 - [(5 + 0.3) / 2 - 0.015]
=100 + 6 - 0.6 - (5 / 2 + 0.3 / 2 - 0.015)
=106 - 0.6 - (2.5 + 0.15 - 0.015)
=105.4 - (2.65 - 0.015)
=105.4 - 2.635
=(102.4 + 3) - (2 + 0.635)
=102.4 + 3 - (2 + 0.635)
=102.4 + (3 - 2 -0.635)
=102.4 + (1- 0.635)
=102.4 + 0.365
=102.765

102.765(計算機)

52.7x1.95
=102.765


呢d冇步驟喎....佢要用直式架..