When the hand passes the number, it will show the time.

If you want to ask how many points you got, please look at the minute hand carefully.

2. Additional songs

When two numbers are added, the result of the addition is called sum.

Don't forget the numbers on the right, one for every ten.

3. The Song of the Meaning of Subtraction

Subtraction is used from big to small, and the result of subtraction is called difference.

Digital alignment starts from the right, and when it is not enough, take the front position.

4. Return? Bit? Minus sign? law

The abdication subtraction should be kept in mind, starting from the unit;

Go ahead when you see 0 to see who has the number;

Borrowed and walked back, 0 is a bit like 9.

Who is not enough to retire, don't forget to add ten to the standard;

If the interval is 1, it is best to remember that 0 becomes 10.

5. Integer addition rule

Integer addition is regular, and the same digits should be aligned.

And less than ten fell in the original position, and more than ten entered one.

Go down for more than ten times, and add whichever one is dropped.

Add up the carry, and the result is not less than half a cent.

6. Integer subtraction rules

Integer subtraction is regular, and the same numbers should be aligned.

Reduce the time and difference greatly, and borrow less.

Minus ten and add it, and the result of addition and subtraction falls in the original position.

Be careful when borrowing continuously, and remember what is left when borrowing.