# Simple mathematical equation in overleaf

I have needed to type a simple mathematical equation into my PhD thesis, on overleaf.

target number = {(a x b)/(c x d)} x constant.

I don't quite know how to use the equation function as I'm new to coding... if someone could please tell me the code that produces the equation above, I would be most thankful.

It would be really good, if the format of the equation could be designed as follows;

1. The content within the curly brackets be written out in two lines, as in (a x b) on top line and (c x d) on the bottom line with the x constant aligned in the middle which would also align with the "target number" on the left hand side.
2. underneath the "target number" on the left hand side, within brackets, write its units (number/ul)

Thank you so much!

Mostly off-topic:

• Overleaf has nothing to do how you write equations ar other math expressions. This is task of LaTeX.
• To make yourself more familiar with LaTeX and the way how to write equation by it, I strongly encourage to consider @daleif comment.

It seems that you in your thesis use quantities. For writing them on proper way in accordance with SI (Système International d’Unités) rules published in CGPM (Conférence Génrale des Poids et Mesures) you should consider to use package siunitx. In its documentation you will find thoroughly explained how to use packages in writing units, quantities and design tables with with collected values.

An MWE (Minimal Working Example) in which consider of use of the siunitx package and mimic desired form of equation can be:


\documentclass{article}
\usepackage{amsmath} % for use of \underset
\usepackage{siunitx}
\sisetup{inter-unit-product=\ensuremath{{}\cdot{}}}

\begin{document}
$$\underset{[\unit{\kilogram\meter\per\second}]} {h} = \frac{a \times b}{c \times d} \times k$$
\end{document}


Note: Usually (in technical texts at least) aren't used dots between units. Also \times are more or less reserved for denote vector product. Without them you will get:

\documentclass{article}
\usepackage{amsmath}
\usepackage{siunitx}

\begin{document}
$$\underset{[\unit{\kilogram\meter\per\second}]} {h} = \frac{ab}{cd} k$$
\end{document}


If your equation is inline you write:

Some text $\frac{ab}{cd}k$ other text.


Output:

If Your equation is alone in a line you can write:

Some text

$\frac{ab}{cd}k$


other text. Output:

• Many thanks for your input Raffaele Santoro Feb 11, 2022 at 10:17
$$\underset{[\mathrm{kg \cdot m \cdot s^{-1}}]}{h} = \frac{a \times b}{c \times d} \times k$$


Some explanations:

There are lots of different possibilities to write an equation in LaTeX. The simplest one is to just use $...$:

$a = b + c$


It's better when your equation is very simple, can hold in one line of text. You can also use $...$ rather than the dollars: it will center your equation and it's better if the equation is bigger.

Finally, $$...$$ do the same than the latter, but they also give a number to your equation. You can even add a label to your equation if you want to cite it in your text for example.

\underset{a}{b} is a command that will place the text a under the text b.

\mathrm{a} will write your text a like a normal one (no italics).

\cdot can put a central dot, \times gives you a multiplication symbol

\frac{a}{b} will write the a and b terms as a fraction, a being numerator, b denominator.

• Dear Balfar, thank you for helping me out. Your answer is the closest to what I want. But there are some changes that I need to make if you could please help. Feb 11, 2022 at 10:18
• You're welcome. If you need more, you can edit your question by adding the others changes needed or you can create a new question if you think the subject is different enough. Feb 11, 2022 at 10:20
• (1) instead of Kg.ms.s-1, how can you add just a simple (number/uM) in that exact format? (2) All words are in italics and bigger font. How to change all the words to Times New Roman 12pt.? (3) Letters I provided are arbitrary, and in my equation, one letter is represented by two words. e.g. a is Cell Volume. When typed these two words, came out as one word - CellVolume. How to seperate them? Many Thanks. Feb 11, 2022 at 10:25