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Quick Math Automated service for answering common math problems. Provides an array of calculators from algebra, equations, inequalities, calculus, matrices, graphs, to numbers. 
Convert It A conversion and calculation center filled with a large variety of measurement and calculator tools, including: currency, finance, date & time, metric to feet, miles to kilometers and more. 
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Math Warehouse Interactive math lessons, calculators, charts and games, worksheets, newsletters and discussion forum. 
Calculators.org Free calculation tools helping users to estimate, compute and compare credit cards, financial and retirement savings, the payment amount for auto, home, business and commercial loans, weight loss, body mass index and advanced mathematics. 
Mega Converter 2 Discover how many seconds old you are, the difference between a gallon in the USA and a gallon in the UK, how many nanometers in an inch, how many quarts in a chaldron and more. Handy scientific calculator is also available. 
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Wessa Mathematical statistics and forecasting calculators including an equation plotter, multiple regression modeling, and a variety of descriptive statistics from variability and concentration to percentiles and correlation. 
 