1, addition formula.

Appendix+Appendix = sum.

Sum = addend+addend.

Addendum = another addend.

Another addend = and-addend.

The position and sum of commutative addends remain unchanged.

2. Subtraction formula.

Minus-Minus = difference.

Difference = minuend-minuend.

Negative difference = negative.

Subtraction = minuend-difference.

Difference+subtraction = subtraction.

Minus = Minus+Difference.

3. Seen from the right, the first digit of a number is a single digit, indicating how many tens, the second digit is a tens, and the third digit is a hundredth, indicating how many hundredths.

20 yuan has two 10 yuan, or 20 yuan has 20 1 yuan.

0 contains 1 tens, or 10 ones.

Reading and writing all start from a high position, that is, writing words, and writing is writing math words.

Write math words before each one and English words after each one.

4. The hour hand is short and the minute hand is long. 1 =60 points. 60 points = 1. 1 min = 15 min.

When the minute hand points to 12, it is the hour time, and when the hour hand points to the number, it is the time.

When the minute hand points to 6, it is half hour, and when the hour hand passes through the number, it is half hour.

There are twelve numbers on the clock face. There are five cells between two numbers, and a * * * has sixty cells.

An hour hand turns a number in an instant, and a minute hand turns a grid in a minute.

When the hour hand just passes the number, it means it's time.