How to use scientific notation in js?

问题

var a = 5.0;
var b = a * 10e-12;
b *= 10e+12
print(b)

Why b equals 500 instead of 5?

As far as I know 10^(-12) equals to 1/(10^12), how can i rewrite the code?

回答1:

Because math. 10e1 is 100 and 10e-1 is 1.

• 10e1 * 10e-1 is 100.
• 10e2 * 10e-2 is 100.
• 10e3 * 10e-3 is 100.

You can very easily extend this to figure out that 10eN * 10e-N is always going to be 100.

If you want actual scientific notation, as in 1 * 10 ^ 2, you want 1e12 and 1e-12.

回答2:

10^-12 × 10¹² = 1

But what you wrote wasn't 10^-12, nor did you write 10¹².

What you wrote was 10 × 10¹² and 10 × 10^-12:

10 × 10¹² × 10 × 10^-12 = 100

100 × 5 = 500

Proper scientific notation is 1e-12 and 1e12. The e stands for "ten to the power of", so you don't need to multiply that value by ten again.

回答3:

"As far as I know 10^(-12) equals to 1/(10^12)" -- that is correct, but 10e-12 actually means 10*10^(-12)

来源：https://stackoverflow.com/questions/27151311/how-to-use-scientific-notation-in-js