Double; Qijian, Canon, Hewlett-Packard, Jiayin, 80g printing paper of these brands are all very good.
But paper can be divided into high white, bright white and pure white. If you print normally, pure white will do. If it's a drawing or something, the higher the whiteness, the clearer it will be printed.
Introduction to A4 paper:
A4 paper is defined by ISO 2 16, and its specification is 21* 29.7 cm (210 mm× 297 mm). Most countries in the world use this international standard for paper size. This standard was first compiled into DIN (DIN 476) by the German Empire in 1922. Although some of its formats were formulated by France at the same time, they were later forgotten. ф o 216defines three groups of paper sizes: a, b and c: Group C paper size is mainly used for envelopes.
The aspect ratio of group A paper size is √ 2: 1, and then the nearest millimeter value is rounded. A0 is defined as paper with an area of one square meter and an aspect ratio of √ 2: 1. The following paper sizes, such as A 1, A2, A3, etc. , are defined as the paper with one digit missing is folded in half along the long side and then discarded to the nearest millimeter value. The size of group B paper is the geometric average of the same number of sheets and one less number of sheets of group A paper. Before the popularization of printers, group B paper was mostly used. Group C paper size is mainly used for envelopes.
People's Republic of China (PRC) national standard GB/T 148- 1997 "Paper size for printing, writing and drawing" is not equivalent to ISO2 16: 1975.
A4 paper is the origin of 2 10mm×297mm.
Reason one:
A rectangle with a length of 2 and a width of x is x and 1 after being folded in half, so in order to ensure similarity, 1:X=X:2 is needed. What's the ratio? When 297 is divided by 2 10, it is 1.4 14, which is close to that. This ratio is exactly the same as the original paper type after a piece of paper is folded in half. If it is not such a ratio, such as 4: 3, then we will find that the shape of the paper is distorted and becomes 3: 2 after being folded in half.
Reason two:
In fact, to meet this ratio, there can be other values, such as 282mm×200mm, or other sizes. However, the value of 2 10mm×297mm is related to 4 in A4. Since the size of A0 paper is 841mm×1189 mm, A4 paper is the size of A0 paper folded four times.
Therefore, the size of A4 paper is 2 10 mm× 297 mm. ..