Calculator for Safari is a simple, lightweight and easy calculator.
This extension adds a calculator button to your browser toolbar.

You can open the calculator while browsing any web page and make easy operations like Addition, Subtraction, Multiplication and Division. You also can use decimals for your operations.

HOW TO USE EXTENSION:
Start by installing the latest macOS updates to make sure that Safari is up to date. You need Safari 12 or later to get Safari extensions from the App Store.
Find and install an extension:
1. Open Safari and choose Safari > Safari Extensions from the menu bar.
2. The App Store opens to the Safari Extensions page, as pictured above. To download and install an extension, click Get or click the price. You might be asked to sign in with your Apple ID.
3. Click Install.
4. After the extension is installed, click Open.
Then return to Safari to turn on the extension you installed:
1. Choose Safari > Preferences.
2. Click Extensions.
3. Select the checkbox next to the extension's name.
All extensions installed from the App Store are automatically kept up to date.

MANAGING EXTENSIONS:
Choose Safari > Preferences, then click Extensions.
– To turn off an extension, deselect its checkbox.
– To uninstall an extension, select the extension and click the Uninstall button. If you can't determine what an extension does, or you don't expect to use it again, you should uninstall it.