iOS apps:
Braining Camp and their website
Also you can use BitsBoard's flashcard game to practice math facts
More Math Resources - link will prompt you to "make a copy" to keep for your reference. This list has several recommendations.
Math and Science simulations: PhET Gizmos
Math apps for iOS devices: More or Less, Math Tablet, Attainment Company:
Chrome extension . Equatio for Chrome
Calculators:
Online: desmos - scientific and other online calculators - use zoom to enlarge on screen
simulators
Large format calculators