What is wrong with math

Trying to multiply 2 digits, but can't get correct answer?

void setup() {
  // put your setup code here, to run once:
Serial.begin(57600);
}

void loop() {
  // put your main code here, to run repeatedly:
 unsigned long k = 600*100;
 k = k/100;
  Serial.print(k,DEC);
  Serial.println();
  delay(1000);

}
unsigned long k = 600UL*100UL;

Please remember to use code tags when posting code.

AWOL:

unsigned long k = 600UL*100UL;

Please remember to use code tags when posting code.

OMG… need to release break fluid from the system…

thanks!