(9分之1-12分之1)×36
=1/9×36-1/12×36
=4-3
=1
8分之5×5.3+5.7×8分之5-0.625
=6.25×(5.3+5.7-1)
=6.25×10
=6.25
9900÷1.25÷80
=9900÷(1.25×80)
=9900÷100
=99
55×66+66×77+77×88+88×77(这小题你最后一个数77打错了,应该是99的)
55×66+66×77+77×88+88×99
=11×11×(5×6 + 6×7 + 7×8 + 8×9)
=121×(70+42+56+72)
=121×200
=24200