1. 2 1 ÷ 5 = 4... 1.

2.32 ÷ 6 = 5 ...2.

In the division of integers, there are only two situations: divisible and non-divisible. The remainder is generated when it is not divisible, so the remainder problem is very important in primary school mathematics.

When it is not divisible, a remainder is generated. The remainder operation: a mod b = c(b is not 0) means that the remainder obtained by dividing the integer a by the integer b is c, for example, 7 ÷ 3 = 2 1.

Attention should be paid to vertical calculation

(1) number alignment.

(2) from the unit.

(3) Decimal one.

Multiply one digit of the transition number vertically by 2. If you need to carry, enter 1 in front, then this unit number will be increased by ten digits, and so on, and this unit number will be added with new operands.

In the vertical calculation of arithmetic square root, because each complement needs to add two digits, when the root number is more than one digit, it is necessary to ensure that the complement can not be sandwiched with decimal points. For example, three digits must be operated separately from hundreds, and ten digits and one digit are added when complement is added.