There is no integer between 3 and 4, and 3 and 4 are adjacent numbers; Integer consists of positive integer, negative integer and 0, and numbers such as-1, -2, -3, 6, 9, 1 1 are all integers; Where 0 and positive integers are collectively called natural numbers, integers greater than 0 are positive integers, and integers less than 0 are negative integers.

Extended reading: summary of mathematics knowledge in primary school 1 grade 6

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.