maths 20%

[westman]

how do i - 20% of a number in php? i tryed...

$my_num = "100";$my_num2 = ($my_num - 20%);

but DW is giving an err plus i would like to save the $my_num2 in the format of 0.00 (example 99 - 20% = 79.20)

[birbal]

$num2=$num1-($num1/5);

it is just a simple math 20% of $num1 is $num1*20/100 which boils down to above equation (($num1/5)http://php.net/number_format for formating number

Edited August 1, 2012 by birbal

[westman]

i tryed...$my_num = "8";$my_num2 = ($my_num * 20 / 100);and i got 1.6i was looking for 6.4how do i get it write?

[birbal]

you need substract the 20% of it from the $my_num1 to get it. what are you geting now is 20% of $my_num1

[westman]

could you give a code demo please

Edited August 1, 2012 by westman

[westman]

got it... $my_num = "8";$my_num2 = ($my_num * 80 / 100);

[Ingolme]

You shouldn't have quotation marks around the 8. You're forcing the engine to convert from a string to a number before doing the operation.

[justsomeguy]

You can just multiply by .8 also.