Melody

If you get confused converting these to decimals you a can always change percentages into fractions.

% means "out of 100"   so 6%=6/100,     17.3%=17.3/100    etc

4%of 40000 = 4/100*40000

4*x+4*3   etc

$$\\\sqrt7((49*x^8)*y^7)\\\\
=\sqrt7*49*x^{15}\\\\$$

or

$$7^{5/2}*x^{15}\\\\
=7^{5/2}*x^{30/2}\\\\
=\sqrt{7^5x^{30}}$$

It worries about becoming unhinged!

25.04*3.005

the first one has 2 dp the second has 3 decimal places so the answer will have 5 decimal places

Now multiply ignoring the decimal places.

If you do not know how to do this look here

These are the equations of 3 lines in 3 dimensions.

Alan and Aziz have discovered that there is no point that all 3 of these lines go through.

The lines are not "concurrent".

I didn'r know that.  Thanks Aziz  

$$\begin{array}{rlll}
3439.96&=&3104.31(1+r/4)^{20}\\\\
3439.96/3104.31&=&(1+r/4)^{20}\\\\
(3439.96/3104.31)^{1/20}&=&1+r/4\\\\
(3439.96/3104.31)^{1/20}-1&=&r/4\\\\
4[(3439.96/3104.31)^{1/20}-1]&=&r\\\\
\end{array}$$

You can finish it on the site calc on the home page.   

Use the site calc on the home page.

5/6*66.6=

$$x^{50}=10\\\\
(x^{50})^{1/50}=10^{1/50}\\\\
x=10^{1/50}\\\\$$

You can enter this into the site calculator as   10^(1/50)