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黄冈小状元四年级简便计算思考题!急!
5年级的
（1）66 X 21 + 19 X 21 + 85 X 19
=(66+19)*21+85*19
=85*21+85*19
=85*(21+19)
=85*40
=3400
(2) 36 X 111 + 888 X 8
=36*111+111*8*8
=36*111+111*64
=(36+64)*111
=100*111
=11100
(3)99 X 99 +199
=99*99+100+99
=99*(99+1)+100
=99*100+100
=9900+100
=10000