9876 9876*77-9877*76

方法一:
【9876 9876*77-9877*76】

9876 9876*77-9877*76

文章插图
9876*77–9877*76
=9876*(76+1)-(9876+1)*76
=(9876*76+9876)-(9876*76+76)
=9876-76
=9800
方法二:
9876*77-9877*76
=9876*77-(9876+1)*76
=9876*77-9876*76-76
=9876*(77-76)-76
=9876-76
=9800
9876*77-9877*76
=(9876*76+9876)-(9876*76+76)
=9870

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