How many squares are there between 1 and 2?

There are 10 cells in the middle of 1cm on the ruler, and each cell is 1mm long.

Ruler, also known as ruler, is a tool for drawing line segments (especially straight line segments) and measuring length. There are usually scales on the ruler to measure the length. Some rulers have holes with special shapes in the middle, such as letters or circles, which are convenient for users to draw pictures. They are usually used to measure length. Generally divided into tape measure, vernier caliper, ruler and ruler. One of Lu Ban's inventions is to draw a right triangle correctly, also called a class ruler, which can tell craftsmen which sizes are irregular and which ones are unlucky according to the rules of divination (geomantic omen).