How to Round Up a Number

How to round a number up in Flutter?

To round up to the nearest whole number in an absolute sense, use ceil if the number is positive and floor if the number is smaller than 0.

The following function rounds numbers up to the closest integer.

static int roundUpAbsolute(double number) {
  return number.isNegative ? number.floor() : number.ceil();
}

Or, use an extension function (6.3.roundUpAbs).

extension Round on double {
  int get roundUpAbs => this.isNegative ? this.floor() : this.ceil();
}

How to roundup to numbers to 500

The usual thing to do is divide by the multiple (500 in your case), round the result, and then multiply by the multiple:

const values = [12263, 12789];
for (const value of values) {
    const result = Math.round(value / 500) * 500;
    console.log(`${value} => ${result}`);
}

How do you round UP a number?

The math.ceil (ceiling) function returns the smallest integer higher or equal to x.

For Python 3:

import math
print(math.ceil(4.2))

For Python 2:

import math
print(int(math.ceil(4.2)))

How to round up the number to tens (always up)

CEILING() looks like the right approach, but we need to work around integer division. This would seem to do what you want:

select val, ceiling(val / 10.0) * 10 as roundvalue
from (values (1), (10), (15), (90), (91), (95), (99)) t(val)

Yields:


val | roundvalue
--: | ---------:
  1 |         10
 10 |         10
 15 |         20
 90 |         90
 91 |        100
 95 |        100
 99 |        100

How to round up number to nearest 100/1000 depending on number, in JavaScript?

You could take the logarithm of ten and round up the value for getting the value.

function roundup(v) {    return Math.pow(10, Math.ceil(Math.log10(v)));}
console.log(roundup(87));   //   100console.log(roundup(776));  //  1000console.log(roundup(2333)); // 10000

How to round a number in C?

You need to import <math.h> header :

#include <math.h> //don't forget to import this !

double a;
a = round(5.05286); //will be rounded to 5.00

This function has analog definitions for every type, which means that you can pass the following types and it'll be rounded to the nearest for every one of them :

double round(double a);
float roundf(float a);
long double roundl(long double a);

How to round a number to n decimal places in Java

Use setRoundingMode, set the RoundingMode explicitly to handle your issue with the half-even round, then use the format pattern for your required output.

Example:

DecimalFormat df = new DecimalFormat("#.####");
df.setRoundingMode(RoundingMode.CEILING);
for (Number n : Arrays.asList(12, 123.12345, 0.23, 0.1, 2341234.212431324)) {
    Double d = n.doubleValue();
    System.out.println(df.format(d));
}

gives the output:

12
123.1235
0.23
0.1
2341234.2125

EDIT: The original answer does not address the accuracy of the double values. That is fine if you don't care much whether it rounds up or down. But if you want accurate rounding, then you need to take the expected accuracy of the values into account. Floating point values have a binary representation internally. That means that a value like 2.7735 does not actually have that exact value internally. It can be slightly larger or slightly smaller. If the internal value is slightly smaller, then it will not round up to 2.7740. To remedy that situation, you need to be aware of the accuracy of the values that you are working with, and add or subtract that value before rounding. For example, when you know that your values are accurate up to 6 digits, then to round half-way values up, add that accuracy to the value:

Double d = n.doubleValue() + 1e-6;

To round down, subtract the accuracy.

Rounding up to the nearest multiple of a number

This works for positive numbers, not sure about negative. It only uses integer math.

int roundUp(int numToRound, int multiple)
{
    if (multiple == 0)
        return numToRound;

    int remainder = numToRound % multiple;
    if (remainder == 0)
        return numToRound;

    return numToRound + multiple - remainder;
}

Edit: Here's a version that works with negative numbers, if by "up" you mean a result that's always >= the input.

int roundUp(int numToRound, int multiple)
{
    if (multiple == 0)
        return numToRound;

    int remainder = abs(numToRound) % multiple;
    if (remainder == 0)
        return numToRound;

    if (numToRound < 0)
        return -(abs(numToRound) - remainder);
    else
        return numToRound + multiple - remainder;
}