Practice subtraction for numbers from 1 to 9999. • Categories: 1 digit, 2 digits, 2-1 digits, 3 digits, 3-2 digits, 4 digits • 4 difficulty levels - zero, easy, normal, hard • 2 swipe modes: 4 answer choices or 2 answer choices • Swipe (in the gray area at the bottom) in the direction of the correct answer • High scores are maintained for each combination of difficulty level, category and swipe mode • Works offline too Best for improving your mental math skills or for revising before a mathematics test.