问题
填空题
计算:53×57-47×43=______.
答案
53×57-47×43,
=53×57-(57-10)×43,
=53×57-57×43+10×43,
=57×(53-43)+10×43,
=57×10+10×43,
=(57+43)×10,
=1000.
计算:53×57-47×43=______.
53×57-47×43,
=53×57-(57-10)×43,
=53×57-57×43+10×43,
=57×(53-43)+10×43,
=57×10+10×43,
=(57+43)×10,
=1000.