Strange Java Math Result [duplicate]

Question

Really simple question but perhaps someone can explain. I have 2 lines of code:

long millisPerYear = 365*24*60*60*1000;
System.out.println("millis per year = " + millisPerYear);

I expect the output of 31 536 000 000 but I get 1 471 228 928.

If I remove the 1000 from the formula the answer is correct but the 1000 pushes it over the edge.

The variables format is Long so it should be 2⁶⁴ in size, plenty big enough. I'm stumped as to why the values isn't being stored accurately.

Answer 1

You are making computation on the right-hand side using only ints. Replace 365 with 365L to perform computation in long.