To practice Adding and Subtracting numbers in order to keep your mind sharp and mathematically sound. One can choose up to what number range is applicable. Small range for primary kids and a larger range for the grown ups. The operation (minus or plus) is randomly generated along with the numbers. I tried getting rid of - 1 and + 1 sums. The results textbox gives you a run down on what you are getting correct and what your wrong answer was. You can use the number pad provided or the keys on your keyboard and the Enter key. Enjoy. Did I get my answers correct? Hmmm!