Problems needing attention in vertical multiplication calculation;

The last digit of two numbers should be aligned.

Try to write as many numbers as possible on it, and write as few numbers on it to reduce the number of multiplications.

Vertical calculation method:

Multiplication:

The i-th bit of one number is multiplied by the j-th bit of another number.

It should be added to i+j- 1 bit of the product.

Department:

For example, 42 divided by 7.

On a scale of 4 [from high to low]. When calculating the division vertically, start from most significant bit, such as: 42 from most significant bit 4; If it is not divisible, such as: 4 is not divisible by 7, then use the highest bit and the next bit to synthesize a number to be divisible until it can be divisible by the divisor; For example, if 4 can't be divided by 7 in 42, then 4 and 2 are combined into a number. If 42 is divided by 7, the quotient is 6.

Mathematically speaking, the order of these four operations is as follows:

1, operation at the same level In an expression, if it only contains operation at the same level, it should be operated from left to right. That is to say, only addition and subtraction, or only multiplication and division are mixed operations, and their operation order is calculated from left to right.

2, the first to second level operation

In an expression, if both first-level operation and second-level operation are included, then the second-level operation should be calculated first, and then the first-level operation should be calculated. That is, "multiply first and then divide, then add and subtract", or "multiply first and then divide, then add and subtract" for short.