1, addition: the same digits are aligned. If the sum exceeds 10, proceed to 1.
2. subtraction: the same numbers are aligned. If it is not enough, borrow 1 from the last digit as 10.
3. The I-th bit of one number multiplied by the J-th bit of another number should be added to i+j- 1 bit of the product.
4. Division: If 42 is 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.
Extended data:
Column vertical method:
(1) Write the first addend in the top line first. If the two digits are different, write the number with more digits first;
(2) Write the second addend on the following line. If the two digits are different, write the one with fewer digits. The second number should be aligned with the digits of the first number;
(3) Write "+"before the second number;
(4) The symbol "=" in the formula is indicated by a horizontal line and written below the second number;
(5) The calculation results of two numbers should be written below the horizontal line and aligned with the numbers above.