1, continuous operation: this kind of problem requires students to find the law in a given series and calculate the next number according to the law. For example, in the sequence 1, 2, 3, 5, 8, 13, students need to find out the rule that each number is the sum of the first two numbers and calculate the next number. This kind of topic can help students master the rules and skills of mathematical operation.
2. Simple operation: This kind of topic requires students to use simple algorithms for quick calculation. For example, when calculating 25× 16, it can be decomposed into 25×4×4, which is easier to calculate. This kind of topic can help students master various simple algorithms and improve the calculation speed and accuracy.
3. Conversion of fractions and decimals: This kind of topic requires students to convert fractions or decimals, or express one number as another. For example, 0.5 is expressed as 1/2 or 3/4 is expressed as 0.75. This kind of topic can help students understand the relationship between fractions and decimals and improve their ability to understand and use mathematical expressions.
Skills of oral calculation:
1. Mastering basic operation rules: The basis of oral calculation is to master basic operation rules, such as addition, subtraction, multiplication and division, and the use of brackets. Only by mastering these basic laws can we do oral calculations correctly.
2. Practice the inverse operation of addition, subtraction, multiplication and division: oral calculation requires quick response and accurate calculation ability, and practicing the inverse operation of addition, subtraction, multiplication and division can help us improve these abilities. For example, if we know that 5+3=8, we can deduce 8-3=5 or 8/2=4 and so on. The practice of these inverse operations can help us to master oral arithmetic skills better.
3. Master some commonly used formulas and skills: Some commonly used formulas and skills in oral calculation can help us to calculate quickly. For example, in multiplication, we can use the skills of distribution law and association law to simplify the calculation process; In division, we can use the technique of quotient invariance and trial quotient to get the result quickly. Mastering these formulas and skills can improve the accuracy and speed of oral calculation.