Interactive
CK-12 Foundation

Addition and Multiplication Properties with Real Numbers: The Secret of Subtraction

For Students 6th - 8th Standards
An interactive boosts mathematicians' knowledge of subtracting integers using a horizontal number line by way of multiple-choice, true or false, and discussion questions. 
Interactive
CK-12 Foundation

Sums of Integers with Different Signs: Adding Between 10 and -10

For Students 6th - 8th Standards
Six questions make up an interactive designed to boost scholars' knowledge of integers. Mathematicians move symbols over a horizontal number line to aid in findings answers between 10 and negative 10. Question types include...
Interactive
University of Illinois

University of Illinois: Mste: The Binary Calculator Applet

For Students 9th - 10th
The binary number system is used to represent data in digital form. This site provides a binary calculator that will convert between binary, octal, decimal and hexadecimal, perform simple addition and subtraction, and do compliment and...
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Scholastic

Scholastic: Math Facts

For Students 3rd - 5th
This one page website from Scholastic offers two math facts games and a secret code idea all to help you remember your math facts.
Interactive
PBS

Pbs Learning Media: Pattern Recognition: Cyberchase Games

For Students K - 1st
Identify the patterns using addition, subtraction, and geometry to solve the puzzle and crack Hacker's code.