Talk about the meaning of the following formula based on the situation: 8x2 4, 50-4x5, 8x7-50

Based on the situation:

What is the sum of 2 times 8 plus 4;

What is the difference of 5 times 50 minus 4;

What is the difference between 7 times 8 minus 50.

Recommend a simple arithmetic method: quick mental arithmetic.

Quick mental arithmetic is not abacus/mental arithmetic/hand-brain arithmetic. It does not require any calculation aids (such as abacus/fingers). You can quickly write the correct answer just by looking at the questions. Quick mental arithmetic is the same as primary school mathematics calculation method. It is consistent, but simpler than primary school textbooks. It is a simple and easy-to-learn calculation method that can really reduce the burden on children.

Quick mental arithmetic - (mental arithmetic, oral arithmetic, written arithmetic) is a teaching model that is truly synchronized with primary school mathematics textbooks. Quick mental arithmetic is currently the only method for simple calculations without the use of any physical objects. Abacus, no fingers either.

1. It starts with the most basic number concepts and links them one by one. It is synchronized with primary school mathematics, but the teaching method is simple and easy for students to accept. In teaching, fast mental arithmetic simplifies complex problems and visualizes abstract mathematical concepts.

2. Niu Hongwei’s fast mental arithmetic makes a good transition between children’s finger counting habits and primary school’s oral arithmetic. It has solved a problem that parents and teachers have not solved for many years. It clears the way for young children to learn oral arithmetic very well.

3. Answer the questions with a pen, without any physical objects (including counting fingers).

4. Quick mental arithmetic problems are calculated from the lower position.