There are several digital tools that can be used to teach mathematics. Some popular ones include:

1. Khan Academy: Khan Academy offers a wide range of math lessons and exercises for students of all levels. It provides interactive videos, practice exercises, and quizzes to help students understand and practice various math concepts.

2. Desmos: Desmos is an online graphing calculator that allows students to plot functions, explore transformations, and analyze data. It also offers a variety of activities and lessons for teaching different math topics.

3. GeoGebra: GeoGebra is a dynamic mathematics software that combines geometry, algebra, and calculus. It allows students to explore mathematical concepts through interactive graphs, spreadsheets, and geometry tools.

4. Mathway: Mathway is an online math problem solver that can help students solve a wide range of math problems. It provides step-by-step solutions and explanations for various math topics, including algebra, calculus, and statistics.

5. Prodigy: Prodigy is a game-based learning platform that offers math practice for students in grades 1-8. It provides adaptive math questions and interactive games to engage students and help them improve their math skills.

These tools can be used by teachers to supplement their lessons, provide additional practice for students, or even facilitate remote learning.