Question

几道的简便计算题

9999X7778+3333X6666 =? 5.6X69.32+138.64X0.05+693.2X0.43=?1234567891的平方—1234567890X1234567892=?362+543X361———————=?362X548—186

Answer 1

9999X7778+3333X6666
=9999×7778 +3333×3×2222
=9999×（7778 +2222）
=9999×10000
=99990000
5.6X69.32+138.64X0.05+693.2X0.43
= 5.6X69.32+69.32×2X0.05+69.32X4.3
=69.32×（5.6+0.1+4.3）
=69.32×10
=693.2
1234567891²—1234567890X1234567892
=1234567891²—1234567890X（1234567891+1）
=1234567891²—1234567891×1234567890—1×1234567890
=1234567891×（1234567891—1234567890）—1234567890
=1234567891—1234567890
=1
最后一题没看懂