Calculator Air
Basic & Scientific calculator features equation preview, dark mode, history, portrait and landscape mode

Math Solver - Free Step-by-Step Calculator
On-line advanced calculator handles algebra, geometry, calculus, probability/statistics, linear algebra, linear programming, and discrete mathematics problems, with steps shown.
https://www.emathhelp.net

Desmos Graphing Calculator
Explore math with our beautiful, free online graphing calculator. Graph functions, plot points, visualize algebraic equations, add sliders, animate graphs, and more.  
Desmos Graphing Calculator Learning Guide  https://learn.desmos.com/graphing

Desmos Graphing Calculator tutorial  https://www.youtube.com/watch?time_continue=2&v=RKbZ3RoA-x4&feature=emb_logo 

The Math Keyboard
The Math Keyboard give you quick access directly in your keyboard to hundreds of useful Math and Scientific characters.

Math Paper
Math Paper allows you to simply touch the screen and do your math by providing all the numbers, symbols, and operations you need. Moreover, thanks to its intuitive and gorgeous interface, it will let all your work look good! Math Paper is great for beginning math and advanced math... with special settings to support your own particular needs.
Math Paper Overview video  http://panthertechnology.com/products/math-paper/#prettyPhoto/0/ 

MathBrush
App that recognizes mathematical expressions as you draw them. It supports variables and functions, not just numbers, and recognizes a wide range of mathematics, including polynomials, integrals, multiple expressions, and matrices. Save your expressions for later, or export them for a document or website.
MathBrush Tutorials  https://www.scg.uwaterloo.ca/mathbrush/guide/ 

Mod Math
An adaptive program to assist students who struggle with Mathematical notation. The app lets you write and solve math problems right onto the touch screen of an iPad using the custom keypad, and you can print, email, or save to cloud services like Dropbox.
Mod Math Overview  http://www.modmath.com/ 

Algebra Touch
Helps refresh your skills using touch-based techniques built from the ground up for your iPhone and iPad.

Photo Math
App that can read and solve problems ranging from arithmetic to calculus instantly by using the camera on your mobile device.  It helps you learn how to approach math problems through clear steps and detailed instructions. 
Photo Math Overview  https://photomath.app/en/ 

Mathway: Math Problem Solver
From basic algebra to complex calculus, Mathway instantly solves your most difficult problems – simply type your problem or snap a pic to receive instant free answers.  Provides detailed step-by-step solutions to show you how the answer was reached.
Mathway tutorial  https://www.mathway.com/Algebra 

Equatio
This software allows you to create mathematical equations, formulas and more directly on your computer. Simply type, handwrite or dictate any expression, and EquatIo will convert it to accurate digital math, which can be added into a Microsoft Word doc or G Suite apps with a click.  Has an iOS mobile app for editing and uploading.
Equatio Overview  https://www.texthelp.com/en-us/products/equatio/ 

Equation Overview Demo Video  https://www.youtube.com/watch?time_continue=4&v=JnVMbjG2PaE&feature=emb_logo 

Equatio Mobile How-To Tutorial  https://www.bing.com/videos/search?q=equatio+mobile&&view=detail&mid=4A308B699F7518C388394A308B699F7518C38839&&FORM=VRDGAR&ru=%2Fvideos%2Fsearch%3Fq%3Dequatio%2Bmobile%26%26FORM%3DVDVVXX