Most of us, when we become professionals,

大多数人我说的是专业人士
don't put in numbers till the very end.

只在最后一步代入数值
So, if you are told the incline is an angle of 37 degrees,

如果已知斜面的倾角是 37°
g is 9.8, don't start putting numbers into the first equation.

g 等于 9.8 不要把数字代进第一个方程
We don't do that and I know

不能这么做而且我知道
for some of you it's pretty traumatic to work with symbols,

对你们中有些人来说符号运算很痛苦
and sometimes on exams they say,

有时在考试的时候他们会说
"Oh, you had all these problems with symbols."

"你的答案怎么全用符号表示的啊"
But I want to sell you another idea.

但我想再给你们灌输一个思想
It's much better

最好的办法是
to work with symbols than with numbers till the end.

用符号算到最后一步而不是用数字
Why is that?

为什么呢