Serial.println(8000*100); return 14464 ????

Hi! Probably it's look pretty stupid....but Subj.

tested on Uno. +,-, / and 8000*100 work fine...

void setup() { 
void loop() {      

Probably you have any explanation of this paradox :)

Ops.... sorry....mistake in subject .... correct is: Serial.println(8000*10); return 14464 ????

Try a cast to unsigned long. 8000UL*10UL

You're using int math. THe largest value an int can hold is 65535. If you try to stuff 80000 in there you get 80000 - 65536 = 14464.

Use longs instead of ints as the last post suggested and your problem will be solved.