计算(能简算的要简算). 8×99+3.8 57-55÷56-1/56.

问题描述:

计算(能简算的要简算).
8×99+3.8                   
57-55÷56-

1
56

(1)8×99+3.8 
=8×(100-1)+3.8
=8×100-8+3.8
=800-8+3.8
=795.8;
(2)57-55÷56-

1
56

=57-55×
1
56
-
1
56

=57-(55×
1
56
+
1
56

=57-(55+1)×
1
56

=57-56×
1
56

=57-1
=56.