几道的简便计算题

题目

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

答案

9999X7778+3333X6666=9999×7778 +3333×3×2222=9999×（7778 +2222）=9999×10000=999900005.6X69.32+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=693.21234567...