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简便计算①86+86×99②289×98③125×4×8×25×5×2④199+1999+19999+199999.

题目详情
简便计算
①86+86×99
②289×98
③125×4×8×25×5×2
④199+1999+19999+199999.
▼优质解答
答案和解析
①86+86×99
=86×(1+99)
=86×100
=8600;
②289×98
=289×(100-2)
=289×100-289×2
=28900-578
=28322;
③125×4×8×25×5×2
=(125×8)×(4×25)×(5×2)
=1000×100×10
=1000000;
④199+1999+19999+199999
=(200-1)+(2000-1)+(20000-1)+(200000-1)
=222200-4
=222196.