wrong float calculation with spriteKit, always getting same result - ios

Question

I'm doing a method which creates you a custom sprite with a platform image and many invisible boxes to do the physic body . In this method I make three principal objects: the sprite image (platform), two "walls" with physics bodies (one at the top left and one at the top right of the sprite) and the ground which are boxes that goes along the ground between the walls.
I want to focus the single line of code which is making troubles.
As you can see in the image, I'm getting a result of 0.600000024 allways, whatever the value of "totalCajas" is. In this case the variable "totalCajas" is equal to 10 and the minaPek.size.width value is always 300 in this case so normally
(minaPek.size.width/500 == 0.6) - (10/100 == 0.1) should be equal to 0.5
So I don't understand why I'm getting this error. Any help would be apreciated!!
Let me explain you two simple things about the method, the param pos (position) are degrees and it's exactly like the x position of the sprite.
The param distMoon is the y position. It's actually the radius.
Size obviously is the size of the sprite. Thank you very much in advance for learnCocos2D cause he is always faster.
-(void)plataformaCustom:(CGFloat)pos Altura:(CGFloat)distMoon size:(CGSize)Size
{
XYZCajas *minaPek = [[XYZCajas alloc]crearMinaMed];
[minaPek setSize:Size];
[minaPek setDistanciaLuna:distMoon];
[self.world addChild:minaPek];
NSArray *temp = [NSArray arrayWithObjects:minaPek, nil];
[objetosMovimiento addObjectsFromArray:temp];
[superCaja setObjectsMovimiento:objetosMovimiento];
//A CONTINUACION creo un int con el numero total de cajas. Me servirá para posteriormente posicionarlas en los extremos/saber cuantos grados tienen
int totalCajas = minaPek.size.width / 20;
//A CONTINUACION Creo un bool que me hará saber cuando tengo colocada la pared izquierda
bool paredIzquierda = NO;
bool paredDerecha = NO;
for (totalCajas; totalCajas >=0; totalCajas--)
{
//APUNTE Cada 100 de ancho de la mina = 0.2 grados de distancia de la pared
// la distancia entre caja y caja es de 0.1
//A CONTINUACION
//coloco la pared izquierda.
if (paredIzquierda == NO)
{
XYZCajas *paredIzq =[[XYZCajas alloc]crearParedSinImagen];
[paredIzq setGrados:-1*(minaPek.size.width/500)];
[paredIzq setDistanciaLuna:distMoon+5];
[paredIzq setName:#"paredIzqPrueba"];
[self.world addChild:paredIzq];
NSArray *temp2 = [NSArray arrayWithObjects:paredIzq, nil];
[objetosCajas addObjectsFromArray:temp2];
[superCaja setObjects:objetosCajas];
paredIzquierda = YES;
totalCajas --;
}
//A CONTINUACION
//coloco la pared derecha
if (paredDerecha == NO)
{
XYZCajas *paredDer =[[XYZCajas alloc]crearParedSinImagen];
[paredDer setGrados:minaPek.size.width/500];
[paredDer setDistanciaLuna:distMoon+5];
[self.world addChild:paredDer];
NSArray *temp2 = [NSArray arrayWithObjects:paredDer, nil];
[objetosCajas addObjectsFromArray:temp2];
[superCaja setObjects:objetosCajas];
paredDerecha = YES;
totalCajas --;
}
//A CONTINUACION
//creamos cajas
XYZCajas *caja22 =[[XYZCajas alloc]crearCajaSinImagen];
float gradosCaja = ((minaPek.size.width/500) - (totalCajas/100));
[caja22 setGrados:gradosCaja];
[caja22 setDistanciaLuna:distMoon+20];
[self.world addChild:caja22];
NSArray *temp2 = [NSArray arrayWithObjects:caja22, nil];
[objetosCajas addObjectsFromArray:temp2];
[superCaja setObjects:objetosCajas];
}