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Math round only a quarter

var number = 0.08;
var newNumber = Math.round(number * 4) / 4 //round to nearest .25

With the above code, I can round to the nearest .25. However, I only want it to round up. Moreover:

0.08 = 0.25
0.22 = 0.25
0.25 = 0.25
0.28 = 0.5

How will this be possible?

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5 answers


What you really want to do is take the ceiling of the input, but instead of working with integers, you want it to work at a quarter. One trick we can use here is to multiply the input by 4 to make it an integer and then expose it to JavaScript functions Math.ceil()

. Finally, divide this result by 4 to bring it back to its logically original start.

Use this formula:

Math.ceil(4 * num) / 4

Demo here:



Rextester

+6


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You might want to Math.ceil()

:

ceil()

round the number up to the nearest whole number.



console.log(Math.ceil(0.08 * 4) / 4);    // 0.25
console.log(Math.ceil(0.22 * 4) / 4);    // 0.25
console.log(Math.ceil(0.25 * 4) / 4);    // 0.25
console.log(Math.ceil(0.28 * 4) / 4);    // 0.5
Run codeHide result


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Tim Bigelissen is definitely the best answer, but if you want a "simpler" approach, you can simply write your own function, for example:

var round = (num) => {
  if (num <= 0.25) {
      return 0.25;
  } else if (num > 0.25 && num <= 0.5) {
      return 0.5;
  } else if (num > 0.5 && num <= 0.75) {
      return 0.75;
  } else if (num > 0.75 && num <= 1.0) {
      return 1.0;
  } else {
      return null;
  }
};

When called, it will reproduce the results you want:

round(0.08); // 0.25
round(0.22); // 0.25
round(0.25); // 0.25
round(0.28); // 0.5
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The user Math.ceil()

performs the function of rounding the number.

Math.floor()

- round down.

var number = 0.08;
var newNumber = Math.ceil($scope.newAmt * 4) / 4 //round to nearest .25
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The big problem is that you are using

Math.round($scope.newAmt * 4) / 4

This will always round based on the standard rounding method as we know it. you can use

Math.ceil($scope.newAmt * 4) / 4

as it will always be rounded. Brother junior -

Math.floor()

by the way.

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