# How can I underline mathematics using a harpoon of variable size?

I am a new user of LaTeX. I want to underline the answers to mathematics problems using a \rightharpoondown symbol. If possible, I would like a \rightharpoondown of variable size, as in the image below. How can I achieve this?

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• I don't understand your question. You mention \rightharpoondown but the link to your example doesn't use it; it circles the answer. Is a circled answer what you are looking for? – Frédéric Jul 7 '13 at 16:20
• Sorry the insufficient my question. I mentioned it follow the two examples. $\overset{5 Volts}{\rightharpoondown}$ $\underset{\rightharpoondown}{4 Volts}$ But \rightharpoondown will be variable. – Özgür Jul 7 '13 at 16:34
• Now that I know you are talking about \rightharpoondown, please explain what is your problem with it, what you actually want to attain. – Frédéric Jul 7 '13 at 16:46

Here is are three macros that (1) underline with a hook, (2) circle an answer (with an ellipse) and (3) that place two diagonal lines in the lower right corner. Note that I used the siunitx package to write the answer; this package is made to correctly write the units of a value.

\documentclass[border=5pt]{standalone}

\usepackage{amsmath}
\usepackage{siunitx}
\usepackage{tikz}
\usetikzlibrary{calc}
\usetikzlibrary{shapes.geometric}

}}

}}

\draw[double, double distance=2pt] ($(answer.south east) + (45:0.2)$) -- ($(answer.south east) - (45:0.2)$);
}}

\begin{document}
$x = \answer{\SI{5}{Volts}} = \answercircled{\SI{5}{Volts}}= \answerside{\SI{5}{Volts}}$

\end{document}


The result is

After that teaching my example, again thank you Frédéric.

 \documentclass[border=5pt]{standalone}

\usepackage{amsmath}
\usepackage{siunitx}
\usepackage{tikz}
\usepackage{color}

\usetikzlibrary{calc}
\usetikzlibrary{shapes.geometric}

$x = \answer{\SI{5.977}{Volts}}$