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# Javascript Arithmetic

### Constants

ConstantsDescriptionApproximate
Math.E Base of natural logarithm e 2.718
Math.LN10Natural logarithm of 10 2.302
Math.LN2 Natural logarithm of 2 0.693
Math.PI Pi: the ratio of circle circumference to diameter (π) 3.14
Math.SQRT1_2 Square root of 1/2 0.707
Math.SQRT2 Square root of 2 1.414
Number.MAX_VALUE Largest positive finite value of Number 1.79E+308
Number.MIN_VALUE Smallest positive value for Number 5E-324
Infinity Value of positive infinity (∞) 0---

### Remainder / Modulus (%)

The remainder / modulus operator (%) returns the remainder after (integer) division.

``````console.log( 42 % 10);
console.log( 42 % -10);
console.log(-42 % 10);
console.log(-42 % -10);
console.log(-40 % 10);
console.log( 40 % 10); ``````

### Output

2
2
-2
-2
-0
0

This operator returns the remainder left over when one operand is divided by a second operand. When the first operand is a negative value, the return value will always be negative, and vice versa for positive values.
In the example above, 10 can be subtracted four times from 42 before there is not enough left to subtract again without it changing sign. The remainder is thus: 42 - 4 * 10 = 2.

The remainder operator may be useful for the following problems:

### Rounding

Math.round() will round the value to the closest integer using half round up to break ties.

``````var a = Math.round(2.3);
var b = Math.round(2.7);
var c = Math.round(2.5); ``````

### Output

a is now 2
b is now 3
c is now 3

But

``````var c = Math.round(-2.7);
var c = Math.round(-2.5);``````

c is now -3
c is now -2

### Rounding up

Math.ceil() will round the value up.

``````var a = Math.ceil(2.3);
var b = Math.ceil(2.7); ``````

### Output

a is now 3
b is now 3

ceiling a negative number will round towards zero

``var c = Math.ceil(-1.1); ``

c is now 1

### Rounding down

Math.floor() will round the value down.

``````var a = Math.ceil(2.3);
var b = Math.ceil(2.7);``````

### Output

a is now 3
b is now 3

ceiling a negative number will round towards zero

``var c = Math.ceil(-1.1);``

c is now 1

## Conclusion

In this page (written and validated by ) you learned about Javascript Arithmetic . What's Next? If you are interested in completing Javascript tutorial, your next topic will be learning about: Javascript Trigonometry.

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