Improve math skills of your kids - Learn step-by-step arithmetic from Math games

Math: Unknown - Step-by-step math calculation game for iOS.

Math: Unknown is much more than a math game. It is a step-by-step math calculation game which will teach users how to calculate in the correct order rather than just asking only the final calculated results.

The app consists of four basic arithmetic operations which are addition, subtraction, multiplication and division. In order to get started, users who are new to arithmetic can learn from animated calculation guides showing step-by-step procedures of solving each type of operation. It is also helpful for experienced users as a quick reference.

Generally, addition and subtraction may be difficult for users who just start learning math especially when questions require carrying or borrowing (also called regrouping). The app helps users to visualize the process of carrying and borrowing in the way it will be done on paper. Once users understand how these operations work, they are ready to learn multiplication and division.

For most students, division is considered as the most difficult arithmetic operation to solve. It is a common area of struggle since it requires prior knowledge of both multiplication and subtraction. To help users understand division, the app uses long division to teach all calculation procedures. Relevant multiplication table will be shown beside the question. Users will have to pick a number from the table which go into the dividend. Multiplication of selected number and divisor is automatically calculated, but the users have to do subtraction and drop down the next digit themselves. Learning whole calculation processes will make them master it in no time.

Math: Unknown is a helpful app for students who seriously want to improve arithmetic calculation skills.

Numerical Methods - First derivative using Excel VBA code

In the previous post, Numerical Methods - First derivative using Excel formula, we know how to calculate the first derivative of functions using formula in Microsoft Excel. In this post, let's see how we can simplify it by using Excel VBA code.

The VBA is just like this.

' ================================================
' Created by Suparerg Suksai
' Mechanical Design Handbook
' http://mechanical-design-handbook.blogspot.com
'
' First Derivative - Numerical Methods
' ================================================

Function f(x As Double) As Double

f = 5 * (x - 3) ^ 3 - 4 * x ^ 2 - Sin(2 * x)
End Function

Function fDeriv(x As Double) As Double
Const
h = 0.00001 ' Step size
fDeriv = (-f(x + 2 * h) + 8 * f(x + h) - 8 * f(x - h) + f(x - 2 * h)) / 12 / h
End Function

The highlighted (yellow) text is the function that we want to calculate for the first derivative. We can simply replace it with new function. The remaining code still remains the same.

We have to put this code into the Microsoft Visual Basic Editor in Microsoft Excel (Alt+F11). Now we're going to test this Derivative code. Because the first derivative of the function in this example can be determined by direct method. Then we can use it to recheck the calculation result.

The first derivative of 5(x-3)3-4x2-sin(2x) is 15(x-3)2-8x-2cos(2x). Therefore the first derivative of f(x) where x = 7 must be 15(7-3)2-8(7)-2cos(2(7)) = 183.7265256

Here how to use

In excel spreadsheet, enter =fDeriv(7) and see the result. We'll use this First Derivative Function in the Newton-Raphson Root Finding Method later.