解:1.94X9.9等于( 9603/500 ),【即等于19.206】
∵已知需求出1.94X9.9等于多少
A × (B - C)= A × B - A × C
∴1.94 X 9.9
= 1.94 × ( 10 - 0.1)
= (1×100+94)/100 × (10 - 1/10)
= 194/100 × (10 - 1/10)
= 97/50 × 10 - 97/50 × 1/10
= 97/5 - 97/500
= 9700/500 - 97/500
= 9603/500
= 19.206
答:1.94X9.9等于( 9603/500 ),【即等于19.206】
简便计算
1.94X9.9
=1.94x(10-0.1)
=1.94x10-1.94x0.1
=19.4-0.194
=19.206
1.94X9.9
=1.94×(10-0.1)
=1.94×10-1.94×0.1
=19.4-0.194
=19.206