This is for math apps on desktop/laptop, tablets, phones and other mobile devices.
Website: http://www.khanacademy.org/
Free iPad app: https://itunes.apple.com/us/app/id469863705?mt=8&at=10l6SU
Free iPhone app: https://itunes.apple.com/us/app/id469863705?mt=8&at=10l6SU
Free Android Phone app: https://play.google.com/store/apps/details?id=org.khanacademy.android
Free Android Tablet app: https://play.google.com/store/apps/details?id=org.khanacademy.android
Edmodo app: https://spotlight.edmodo.com/product/khan-academy,324527/
Free iPad app: https://itunes.apple.com/us/app/educreations-interactive-whiteboard/id478617061?mt=8&at=10l6SU
Website: http://www.sumdog.com/
Website: http://www.mathworksheetsland.com/
Website: http://learnzillion.com/
Website: https://www.funbrain.com/
Website: http://www.mathplayground.com/
Free iPad app: https://itunes.apple.com/us/app/mathletics-student/id560955922?mt=8&uo=4&at=10l6SU
Free iPad app: https://itunes.apple.com/us/app/math-champ-host/id516219390?mt=8&uo=4&at=10l6SU
Free iPad app: http://itunes.apple.com/us/app/motion-math-zoom/id451793073?mt=8&uo=4&at=10l6SU
Free iPhone app: http://itunes.apple.com/us/app/motion-math-zoom/id451793073?mt=8&uo=4&at=10l6SU
Website: http://www.mangahigh.com/
Free iPhone app: https://itunes.apple.com/us/app/motion-math-wings/id508228412?mt=8&uo=4&at=10l6SU
Free iPad app: https://itunes.apple.com/us/app/motion-math-wings/id508228412?mt=8&uo=4&at=10l6SU
Free iPad app: https://itunes.apple.com/us/app/mathmateer-free/id408770902?mt=8&uo=4&at=10l6SU
Paid iPad app: https://itunes.apple.com/us/app/mathmateer/id393989284?mt=8&uo=4&at=10l6SU
Free iPhone app: https://itunes.apple.com/us/app/mathmateer-free/id408770902?mt=8&uo=4&at=10l6SU
Paid iPhone app: https://itunes.apple.com/us/app/mathmateer/id393989284?mt=8&uo=4&at=10l6SU