用简便方法计算:19×27+19

问题描述:

用简便方法计算:19×27+19

法一:
19 × 27 + 19
= 19 ×(27 + 1)
= 19 × 28
=(20 - 1)× 28
= 20 × 28 - 1 × 28
= 560 - 28
= 532
法二:
19 × 27 + 19
=(20 - 1)× 27 + 19
= 20 × 27 - 27 + 19
= 540 - 8
= 532