How to quickly calculate two digit multiplication (two digit multiplication and division)
It can be calculated in this way, for example, 53 × 89 = 53 × 90-53 = 4770-53 = 4717, or 67 × 91 = 67 × 90 + 67 = 6097, which still depends on a little computing power. There is also an algorithm: for example, 38 × 94 can be regarded as 3 × 9 × 100 + (3 × 4 + 8 × 9) × 10 + 4 × 8 = 2700 + 840 + 32 = 3572