of cyber flash-cards for Addition, Subtraction, Multiplication, and
Division. It allows you to drill each function at 7 different levels,
and keeps statistics on when you did the drill, how long it took, and
the numbers and kinds of errors. It alwo provides a cryptographic check
sum so that your teacher can verify that you did the work.
Ever wonder whether your telephone number or Social Security number
is prime, or what is the closest prime to some big number?
Puzzle no more, this page will give you the answers!
It has now been updated to handle "Safe" prime calculations. A Safe prime
is a prime P where (P-1)/2 is also prime.
This page gives you an opportunity to practice factoring quadratic equations.
Set the limits for the factors and click the "New Quadratic" button to generate
a new random quadratic equation for you to factor. Then click the "Show Factors"
button to reveal the prime factors of the quadratic. This will provide you with
hours of fun!
This is an offshoot of the old 711 problem. A clerk multiplies the prices of a
customer's four purchases and gets $7.11. The customer complains that the
prices should be added, not multiplied. The clerk adds them and gets the same result. So what are the four numbers?
Here is a calculator to help you, and another puzzle where the four prices have a product and sum of $20.09. Good Luck!
Pythagorean Triples are groups of 3 positive integers which have the property
that a2 + b2 = c2. They are so called because
a triangle with sides of these lengths is a right triangle, and therefore
illustrate the Pythagorean Theorem. This calculator lets you find Pythagorean
Triples that have a particular leg length or hypotenuse and search ranges of
leg or hypotenuse lengths to find all Pythagorean Triples in the range.
Synthetic Division is a useful shortcut when you want to know the value of a
polynomial function for a particular variable value, or to find factors/roots.
The drawback of Synthetic Division is that, as usually demonstrated, it does not
handle complex roots or coefficients. This page shows how to fix that, and
This version is preliminary, and will probably change soon.