计算 9999×7778+3333×6666 1/20+1/30+1/42+1/5
1个回答

9999×7778+3333×6666

=9999×7778+9999×2222

=9999×(7778+2222)

=9999×10000

=99990000

1/20+1/30+1/42+1/56+1/72+1/90

=1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8+1/8-1/9+1/9-1/10

=1/4-1/10

=3/20