两位数乘以两位数速算法五种以上（两位数乘以两位数哪种方法最快）

12×11

=120+12

=132

48×25

=12×4×25

=12×100

=1200

88×13

=8×11×13

=8×143

=1144

55×99

=55×(100–1)

=5500–55

=5445

78×55

=70×55+8×55

=3850+440

=4290