1. discard the fractional part and keep the integer part parseInt (5/2) 2. rounded up. If there is a decimal number, add 1Math to the integer. ceil (5/2) 3, rounded down. math. round (5/2) 4, round down Math. floor (5/2) Math object method FF: Firefox, N: Netscape, IE: Internet Explorer method description ff n ie abs (x) returns the absolute value of the number 1 2 3 acos (x) returns the arccosine of the number 1 2 3 asin (x) returns the arcsin of the number 1 2 3 atan (x) returns the arc tangent value of x between-PI/2 and PI/2 radian. The value is 1 2 3 atan2 (y, x) and returns the value from the x-axis to the point (x, y) angle (between-PI/2 and PI/2 radian) 1 2 3 ceil (x) to round up a number. 1 2 3 cos (x) returns the cosine of the number 1 2 3 exp (x) returns the e index. 1 2 3 floor (x) switches a number down. 1 2 3 log (x) returns the natural logarithm of the number (Base e) 1 2 3 max (x, y) returns the highest values in x and y 1 2 3 min (x, y) returns the lowest value of 1 2 3 pow (x, y) In x and y, returns the power of y x, which is 1 2 3 random (), and returns 0 ~ Random number between 1 1 2 3 round (x) rounds a number into the nearest integer 1 2 3 sin (x) returns the sine of the number 1 2 3 sqrt (x) returns the square root of a number 1 2 3 tan (x) returns the tangent of an angle 1 2 3 toSource () representing the source code of the object 1 4-valueOf () returns the original value of a Math object. math. abs (num): returns the absolute value of num 2. math. acos (num): returns the arc cosine of num 3. math. asin (num): returns the arcsin value of num 4. math. atan (num): returns the arc tangent value of num 5. math. atan2 (y, x): returns the arc tangent value of the quotient dividing y by x 6. math. ceil (num): returns the smallest integer greater than num 7. math. cos (num): returns the cosine of num 8. math. exp (x): returns the number 9 of x power based on the natural number. math. floor (num): returns the maximum integer 10 less than num. math. log (num): returns the natural logarithm of num 11. math. max (num1, num2): returns a large value of 12 in num1 and num2. math. min (num1, num2): return a smaller 13 in num1 and num2. math. pow (x, y): returns the value 14 to the power of y of x. math. random (): returns a random number between 0 and 1. math. round (num): return the value 16 after num rounding. math. sin (num): returns the sine of num 17. math. sqrt (num): returns the square root of num 18. math. tan (num): returns the tangent of num 19. math. e: Natural Number (2.718281828459045) 20. math. LN2: natural logarithm of 2 (0.6931471805599453) 21. math. LN10: 10 natural logarithm (2.302585092994046) 22. math. LOG2E: log 2 is the base natural number (1.4426950408889634) 23. math. LOG10E: The base Natural Number of log 10 (0.4342944819032518) 24. math. PI: π (3.141592653589793) 25. math. SQRT1_2: the square root of 1/2 (0.7071067811865476) 26. math. SQRT2: square root of 2 (1.4142135623730951)