(36-28)乘(423+8)怎么简算?1000-(786+630÷9）怎么简算?

(36-28)×(423+8)
= 8×431
= 8×(400+31)
= 8×400+8×31
= 3200+248
= 3448
1000-(786+630÷9)
= 1000-(786+70)
= 1000-856
= 1000-(850+6)
= 1000-850-6
= 150-6
= 144