knitr kable 和“*”

Question

我正在尝试在单元格中生成一个带有“*”作为值的表格：

---
title: "Untitled"
author: "James Durant"
date: "November 7, 2017"
output: pdf_document
---

```{r arthmatic, echo=FALSE}
library(knitr)
dfx <- data.frame(
  Operator = c("+", "-", "*", "/", "^", "**", "%%", "%/%"),
  Operation = c("addition", "subtraction", "multiplication", 
                "division", "exponentiation", "exponentiation",
                "modulus", "integer division")
  )
kable(dfx, escape = FALSE)
```

但是 * 和 ** 没有出现在表格中：

有什么想法吗？

Answer 1

将每个* 替换为\\text{*} 或\\textasteriskcentered