1, homophonic memory method. For example, in 229, Sun's Rising can read the middle "2" as "2", so 229 becomes "Er Liang Jiu (9)". He also joked that Sun Quan became an emperor after drinking Er Liang Jiu, which was very impressive and soon remembered.

2. Image memory method. For example, in 1777, the United States won the battle of Saratoga in the War of Independence. "7" is very similar to the hoe used by farmers. A group of American farmers, carrying three hoes (1777), defeated the British colonists in Saratoga and won a great victory in the War of Independence.

3. Analyze the characteristics of number arrangement to promote memory. Some time figures are regular. It will be much easier to remember if you pay attention to these rules. For example, multiples of 100 (1900), numerical symmetry (626,676), even overlap (19 19) and so on.

4. Contrast memory method. We can put relevant historical events together and remember them by comparison. For example, the beginning of modern world history is 1640, China is 1640, and China is 200 years behind the world. Just remember this, remember one of the times, and the other time can be calculated.