Math CentralQuandaries & Queries


Question from Colleen:

I work out my claimable gst each month but need to know the total sales or purchases amounts for filling in my six monthly paper work. How do I do that. I tried doing the opposite of calculating the gst i.e. x3 and /23 but it is slightly different to my total.

Hi Colleen,

In Canada our GST rates are not the same as yours so I am not sure where you use "x3" and "/23". Can you send us an example of how you calculate the GST?


Colleen replied

Our GST is $15\%$ I calculate it if it already in by X 3 then / by 23 and if it is not in, by X$15\%$ As I do transfers and have some personal stuff in my accounts as well as business I just have my ledger set up for taking $15\%$ of everything unless I put a 1 in a column. This month my calculated GST in one account was $\$5,419.62$ but when I totalled the gross ($\$40,495.73$) it came out as $\$5,282.05$. Very frustrating.

Hi Colleen,

First of all $\frac{3}{23}=0.1304$ which is $13.04\%$ and $13.04\%$ of $\$40,495.73$ is $\$5,282.05$. I'm not sure where the $\$5,419.62$ comes from.

What am I missing?

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