Is there a way to make the Greek letters displayed upright (non-italic)?

Asked in comment. There is a way using unicode characters, for which one can search here: http://unicode-table.com/en. Normal use of phi is $\phi = ...$, which gives $\phi = ...$.
Looking up phi on the above site gives a couple of results, if one uses 'Greek Capital Letter Phi' and copy it with 'Click to copy and paste symbol', and use it like
$Φ = ...$, the result is $Φ = ...$.
One might need to experiment which symbol(s) look(s) right.

Is there a tool to visually edit (prepare) the formulas with pre-defined symbols and paste here?

For some of the formulas one can use a word processor app that supports formula edition. E.g. one can use MS Word to construct the formula, or even better use the existing pre-defined ones, like I did with the Binomial theorem, then simply select it, and copy-paste here between the desired number of $'s:

$$ \left(x+a\right)^n=\sum_{k=0}^{n}{\binom{n}{k}x^ka^{n-k}} $$

If it does not look right, it might still be less time to adjust the expression than starting it from scratch, or trying to draw by hand such a thing like the above.

Is there a way to make the Greek letters displayed upright (non-italic)?

Asked in comment. There is a way using unicode characters, for which one can search here: http://unicode-table.com/en. Normal use of phi is $\phi = ...$, which gives $\phi = ...$.
Looking up phi on the above site gives a couple of results, if one uses 'Greek Capital Letter Phi' and copy it with the button below its picture, and use it like
$Φ = ...$, the result is $Φ = ...$.
One might need to experiment which symbol(s) look(s) right.

Is there a tool to visually edit (prepare) the formulas with pre-defined symbols and paste here?

For some of the formulas one can use a word processor app that supports formula edition. E.g. one can use MS Word to construct the formula, or even better use the existing pre-defined ones, like I did with the Binomial theorem, then simply select it, and copy-paste here between the desired number of $'s:

$$ \left(x+a\right)^n=\sum_{k=0}^{n}{\binom{n}{k}x^ka^{n-k}} $$

If it does not look right, it might still be less time to adjust the expression than starting it from scratch, or trying to draw by hand such a thing like the above.

One can also use MS Word to construct the formula, or even better use the existing pre-defined ones, like I did with the Binomial theorem, then simply select it, and copy-paste here between the desired number of $'s:

$$ \left(x+a\right)^n=\sum_{k=0}^{n}{\binom{n}{k}x^ka^{n-k}} $$

If it does not look right, it might still be less time to adjust the expression than starting it from scratch, or trying to draw by hand such a thing like the above.

Is there a way to make the Greek letters displayed upright (non-italic)?

Asked in comment. There is a way using unicode characters, for which one can search here: http://unicode-table.com/en. Normal use of phi is $\phi = ...$, which gives $\phi = ...$.
Looking up phi on the above site gives a couple of results, if one uses 'Greek Capital Letter Phi' and copy it with 'Click to copy and paste symbol', and use it like
$Φ = ...$, the result is $Φ = ...$.
One might need to experiment which symbol(s) look(s) right.

Is there a tool to visually edit (prepare) the formulas with pre-defined symbols and paste here?

For some of the formulas one can use a word processor app that supports formula edition. E.g. one can use MS Word to construct the formula, or even better use the existing pre-defined ones, like I did with the Binomial theorem, then simply select it, and copy-paste here between the desired number of $'s:

$$ \left(x+a\right)^n=\sum_{k=0}^{n}{\binom{n}{k}x^ka^{n-k}} $$

If it does not look right, it might still be less time to adjust the expression than starting it from scratch, or trying to draw by hand such a thing like the above.