# How does one add set symbols in manim?

## Question:

I’m trying to write the set of natural and real numbers in manim using MathTex, but I haven’t found a way that works. Every time I try to use shortcuts I’ve searched up about LaTeX, such as N, natnums, mathbb{N}, and such don’t work, returning the error message:

TypeError: ‘numpy.ndarray’ object is not callable

Does anyone have a solution to this?

Here is the troublesome part in the current version of my code:

NtoR=MathTex(r"natnums","longrightarrow",r"reals")

self.play(Write(NtoR,RIGHT*2))

As previously mentioned, I get the following error message:

TypeError: ‘numpy.ndarray’ object is not callable.

## Answers:

Try adding the amsfonts package to your manim code:

```
class WriteNaturalNumber(Scene):
def construct(self):
myTemplate = TexTemplate()
myTemplate.add_to_preamble(r"usepackage{amsfonts}") # adds package to construct
# Write the symbol
tex = Tex(
r"$mathbb{N}$",
tex_template=myTemplate,
font_size=144,
)
self.add(tex)
```

Result: