First, the sum difference problem. Given the sum and difference of two numbers, find these two numbers.

Formula:

And the sum and the difference are getting bigger and bigger;

Divided by 2, it is big;

And subtract the difference, the smaller the reduction;

Divided by 2, it is small.

Second, the problem of chickens and rabbits in the same cage.

Formula:

Suppose all chickens, suppose all rabbits.

How many feet are there? How many feet are missing?

Divided by the foot difference, it is the number of chickens and rabbits.

Third, the problem of concentration.

1, diluted with water.

Formula:

Sugar before adding water, sugar water after adding sugar.

Sugar water MINUS sugar water is the amount of sugar added.

2. Add sugar to thicken.

Formula:

Water before adding sugar, syrup after adding water.

If you subtract sugar water from sugar water, you can easily solve the problem.

Fourth, the problem of distance.

1, encountered a problem.

Formula:

At the moment we met, the distance disappeared.

Divide by the sum of the speeds and you get the time.

Step 2 catch up with the problem

Formula:

Slow birds fly first, fast birds chase after them.

The distance to go first, divided by the speed difference,

The time is right.

5. Engineering problems.

Formula:

The total project amount is set to 1,

1 divided by time is work efficiency.

When a person does it, the work efficiency is his own.

When doing it together, the work efficiency is the sum of everyone's efficiency.

1 Subtract what has been done and what has not been done.

What is not completed divided by work efficiency is the result.

6. profit and loss problem.

Formula:

Full profit and loss, greatly reduced;

One profit and one loss, the profit and loss add up.

Divided by the difference in distribution,

The result is the distribution of things or people.

Seven, cattle grazing problem.

Formula:

The amount of grass eaten by each cow per day is assumed to be 1.

How much grass did A eat in the first b days?

How much grass did M eat in the first n days?

Subtract the big one from the small one and divide it by the difference of the corresponding days.

The result is the growth rate of grass.

The original amount of grass is correspondingly reversed.

The formula is the amount of grass eaten by A on the first day minus the amount of grass eaten on the second day multiplied by the growth rate of grass.

Cattle with unknown grazing amount are divided into two parts:

A small number eat new grass first, and the number is the proportion of grass;

Divide some grass by the number of remaining cows to get the required number of days.

Eight, the age problem.

Formula:

The precession will not change, when adding and subtracting.

With the change of age, the multiple is also changing.

Grasp these three points and everything will be easy.

Nine, and the proportion problem. It is known that the whole is divided into parts.

Formula:

Family members want everyone to be together, and separation is also principled.

Denominator ratio sum, numerator's own.

And multiply by the ratio, you deserve it.

Ten, the difference ratio problem.

Formula:

I am more than you, and multiples are cause and effect.

Actual difference of numerator, multiple difference of denominator.

The quotient is double,

Multiplied by their respective multiples,

You can get two numbers.

Mathematics learning methods in the fourth grade of primary school;

1, thinking: thinking is the core of mathematics learning methods. Thinking is of great significance in learning this course. When solving math problems, we should first observe, analyze and think. Thinking can often find out the characteristics of the topic and find the breakthrough and simple method to solve the problem.

2, hands-on try: hands-on help digest what you have learned, so as to achieve mastery. I often deduce the formula that the teacher said after class. Don't read, recite. So that you can master the formula thoroughly.

3. Cultivate the spirit of creativity: The so-called creativity means thinking of new methods, making new achievements and establishing new theories. Creation is not limited to the methods and textbooks taught by teachers.