help needed with a percentage calculation

Question

so in this example when i calculate 10000+1% its shows 10100 but with my casio fx 991 es plus shows 10000.01 please help I'm stuck

Answer 1

It's a matter of interpretation, as $10,000+1\%$ is ambiguous.

Do you mean $10,000+1\%$ as "$10,000$, plus $1\%$ of $10,000$?" If so, then the calculation is

$$10,000+1\% = 10,000+ (0.01 \cdot 10,000) = 1.01 \cdot 10,000 = 10,100$$

Do you instead mean "$10,000$ plus $1/100$?" After all, $1\%$ and $0.01$ are effectively the same thing. In that case, then, the calculation is

$$10,000 + 1\% = 10,000 + 0.01 = 10,000.01$$

Your calculators likely handle these in different ways, though you probably meant the first. In that case, it's best to convert to the the form where you multiply.

More generally, if you want to find "$n$ plus $p\%$ of $n$", you can calculate it as

$$n + \frac{p}{100} \cdot n = \left( 1 + \frac{p}{100} \right) \cdot n$$