Incorrect multiplication answer

Question

I understand that JS math is not perfect. but how can i format this to get the correct answer as I have a cart item which costs .60 cents and they can change the quantity?

var a=3*.6;
document.write(a);

writes 1.7999999999999998

Obviously I want to write 1.8. any ideas how to accomplish this?

Answer 1

Use toFixed to round it back:

var a = 3*.6;
document.write(a.toFixed(2));

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If you need it as a number, add a + sign before it:

var a = 3*.6;
console.log(+a.toFixed(2)); // Logs: 1.8, instead of "1.80"

Answer 2

var a=3*.6;
a = Math.round(a*10)/10;
document.write(a);

Since you want to round to the 10ths place, you need to multiply the number by 10, round the result of that multiplication to the nearest whole number, and then divide the result by 10.

It's not sexy, but ya gotta do whatchya gotta do.