When mixing operations, brackets are needed for the part that needs to be calculated first; The calculation method of mixed operation is: from left to right, multiply first and then divide, then add and subtract; In the continuous calculation of multiplication and division, it should be calculated from left to right; When you encounter parentheses, you must first calculate the inside of parentheses.

Primary school 1-6 grade mathematics mainly studies basic calculation and preliminary understanding of geometric algebra. Basic concepts in numbers and algebra, such as numbers, natural numbers, positive numbers, negative numbers, etc. The basic concepts of graphics and geometry such as angle, fixed point of angle, edge of angle, triangle and quadrilateral.

The first grade of primary school: 99 multiplication formula, learn basic addition and subtraction multiplication formula: recite 99 multiplication formula well and be familiar with single-digit multiplication formula;

The second grade of primary school: improve the multiplication formula table, strengthen the knowledge of the first grade, and learn the mixed operation of division and basic geometry;

The third grade of primary school: learn multiplication and commutation law, geometric area perimeter, time and unit. Distance calculation, distribution law, fractional decimal;

The fourth grade of primary school: the natural number of line angle is an integer, the prime factor is trapezoidal symmetry, and the fraction is calculated;

The fifth grade of primary school: multiplication and division of fractions and decimals, algebraic equations and average values, comparative size transformation, graphic area and volume;

Sixth grade: proportional percentage probability, circular fan, cylinder and cone.