# How to round float numbers in javascript?

## How to round float numbers in javascript?

I need to round for example 6.688689 to 6.7, but it always shows me 7.
My method:
Math.round(6.688689);
//or
Math.round(6.688689, 1);
//or
Math.round(6.688689, 2);

But result always is the same 7… What am I doing wrong?

### Solution 1:

``````Number((6.688689).toFixed(1)); // 6.7
``````

### Solution 2:

``````var number = 6.688689;
var roundedNumber = Math.round(number * 10) / 10;
``````

### Solution 3:

Use `toFixed()` function.

``````(6.688689).toFixed(); // equal to 7
(6.688689).toFixed(1); // equal to 6.7
(6.688689).toFixed(2); // equal to 6.69
``````

### Solution 4:

You can use helper function from MDN example. Than you’ll have more flexibility:

``````Math.round10(5.25, 0);  // 5
Math.round10(5.25, -1); // 5.3
Math.round10(5.25, -2); // 5.25
Math.round10(5, 0);     // 5
Math.round10(5, -1);    // 5
Math.round10(5, -2);    // 5
``````

Upd (2019-01-15). Seems like MDN docs no longer have this helper funcs. Here’s a backup with examples:

``````// Closure
(function() {
/**
* Decimal adjustment of a number.
*
* @param {String}  type  The type of adjustment.
* @param {Number}  value The number.
* @param {Integer} exp   The exponent (the 10 logarithm of the adjustment base).
* @returns {Number} The adjusted value.
*/
function decimalAdjust(type, value, exp) {
// If the exp is undefined or zero...
if (typeof exp === 'undefined' || +exp === 0) {
return Math[type](value);
}
value = +value;
exp = +exp;
// If the value is not a number or the exp is not an integer...
if (isNaN(value) || !(typeof exp === 'number' && exp % 1 === 0)) {
return NaN;
}
// If the value is negative...
if (value < 0) {
return -decimalAdjust(type, -value, exp);
}
// Shift
value = value.toString().split('e');
value = Math[type](+(value[0] + 'e' + (value[1] ? (+value[1] - exp) : -exp)));
// Shift back
value = value.toString().split('e');
return +(value[0] + 'e' + (value[1] ? (+value[1] + exp) : exp));
}

// Decimal round
if (!Math.round10) {
Math.round10 = function(value, exp) {
return decimalAdjust('round', value, exp);
};
}
// Decimal floor
if (!Math.floor10) {
Math.floor10 = function(value, exp) {
return decimalAdjust('floor', value, exp);
};
}
// Decimal ceil
if (!Math.ceil10) {
Math.ceil10 = function(value, exp) {
return decimalAdjust('ceil', value, exp);
};
}
})();
``````

Usage examples:

``````// Round
Math.round10(55.55, -1);   // 55.6
Math.round10(55.549, -1);  // 55.5
Math.round10(55, 1);       // 60
Math.round10(54.9, 1);     // 50
Math.round10(-55.55, -1);  // -55.5
Math.round10(-55.551, -1); // -55.6
Math.round10(-55, 1);      // -50
Math.round10(-55.1, 1);    // -60
Math.round10(1.005, -2);   // 1.01 -- compare this with Math.round(1.005*100)/100 above
Math.round10(-1.005, -2);  // -1.01
// Floor
Math.floor10(55.59, -1);   // 55.5
Math.floor10(59, 1);       // 50
Math.floor10(-55.51, -1);  // -55.6
Math.floor10(-51, 1);      // -60
// Ceil
Math.ceil10(55.51, -1);    // 55.6
Math.ceil10(51, 1);        // 60
Math.ceil10(-55.59, -1);   // -55.5
Math.ceil10(-59, 1);       // -50
``````

### Solution 5:

``````> +(6.688687).toPrecision(2)
6.7
``````

A `Number` object in JavaScript has a method that does exactly what you need. That method is `Number.toPrecision([precision])`.

Just like with `.toFixed(1)` it converts the result into a string, and it needs to be converted back into a number. Done using the `+` prefix here.

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simple benchmark on my laptop:

``````number = 25.645234 typeof number
50000000 x number.toFixed(1) = 25.6 typeof string / 17527ms
50000000 x +(number.toFixed(1)) = 25.6 typeof number / 23764ms
50000000 x number.toPrecision(3) = 25.6 typeof string / 10100ms
50000000 x +(number.toPrecision(3)) = 25.6 typeof number / 18492ms
50000000 x Math.round(number*10)/10 = 25.6 typeof number / 58ms
string = 25.645234 typeof string
50000000 x Math.round(string*10)/10 = 25.6 typeof number / 7109ms
``````

### Solution 6:

See below

`var original = 28.59;`

`var result=Math.round(original*10)/10` will return you returns `28.6`

Hope this is what you want..