解:(1)64

×

,
=63

×

,
=63×

+

,
=7+

,
=7

;
(2)

×35+

×17,
=

7+

×17,
=

(7+17),
=

24,
=20;
(3)3.5×

+1.25×

+3.8÷

,
=3.5×1

+1.25×2.7+3.8×

,
=(3.5+2.7+3.8)×1.25,
=10×1.25,
=12.5;
(4)1998÷1998

=1998÷

,
=1998÷

,
=1998÷

,
=1998×

,
=

;
(5)

×

+

×

,
=


+

,
=

(

),
=

1,
=

;
(6)

×

+

×

+

×

.
=



×

,
=

(

+


。,
=


,
=

.
分析:(1)64

×

,轉(zhuǎn)化為63

×

,在應用乘法分配律進行簡算;
(2)

×35+

×17 轉(zhuǎn)化為

7+

×17,應用乘法分配律簡算;
(3)3.5×

+1.25×

+3.8÷

,把出數(shù)

轉(zhuǎn)化數(shù)乘

,應用乘法分配律叫做簡算;
(4)1998÷1998

,把帶分數(shù)化成假分數(shù),根據(jù)乘法分配律簡算;
(5)

×

+

×

,轉(zhuǎn)化為


+

,應用乘法分配律簡算;
(6)

×

+

×

+

×

轉(zhuǎn)化為



×

,應用乘法分配律進行簡算.
點評:此題主要考查應用整數(shù)乘法的運算定律對分數(shù)四則混合運算進行簡便計算.