Method 1:

1, use sogou input method, find the status bar, and then right click;

2. Find the expression & symbol in the status bar, then find the symbol encyclopedia, and click Open;

3. Enter "divide" in the search box, and then you can find "∫" in the results. When using, click with the left key.

Method 2:

1, right-click the status bar of sogou input method and find the soft keyboard-mathematical symbol;

2. Click to open the special symbol, and you can find the "∫" symbol from the pop-up soft keyboard. When using, click with the left key.