The current answers all focus on decimal digits, when applying the “add all digits and see if that divides by 3”. That trick actually works in hex as well; e.g. 0x12 can be divided by 3 because 0x1 + 0x2 = 0x3. And “converting” to hex is a lot easier than converting to decimal. Pseudo-code: … Read more
It’s because you’re doing integer division. Divide by a double or a float, and it will work: double scale = ( n / 1024.0 ) * 255 ; Or, if you want it as a float, float scale = ( n / 1024.0f ) * 255 ;
Use div, which performs integer division: halfEvens :: [Int] -> [Int] halfEvens [] = [] halfEvens (x:xs) | odd x = halfEvens xs | otherwise = x `div` 2 : halfEvens xs The (/) function requires arguments whose type is in the class Fractional, and performs standard division. The div function requires arguments whose type … Read more
3 and 6 are both Int, and dividing one Int by another gives an Int: that’s why you get back 0. To get a non-integer value you need to get the result of the division to be a non-integer value. One way to do this is convert the Int to something else before dividing it, … Read more
You can call int() on the end result: >>> int(2.0) 2
The guy who said “leave it to the compiler” was right, but I don’t have the “reputation” to mod him up or comment. I asked gcc to compile int test(int a) { return a / 3; } for an ix86 and then disassembled the output. Just for academic interest, what it’s doing is roughly multiplying … Read more
Many languages have a “mod” or “%” operator that gives the remainder after division with truncation towards 0; for example C, C++, and Java, and probably C#, would say: (-11)/5 = -2 (-11)%5 = -1 5*((-11)/5) + (-11)%5 = 5*(-2) + (-1) = -11. Haskell’s quot and rem are intended to imitate this behaviour. I … Read more
Do floating point division then convert to an int. No extra modules needed. Python 3: >>> int(-1 / 2) 0 >>> int(-3 / 2) -1 >>> int(1 / 2) 0 >>> int(3 / 2) 1 Python 2: >>> int(float(-1) / 2) 0 >>> int(float(-3) / 2) -1 >>> int(float(1) / 2) 0 >>> int(float(3) / … Read more
Let me restart for the third time. We are trying to accelerate q = x / y where y is an integer constant, and q, x, and y are all IEEE 754-2008 binary32 floating-point values. Below, fmaf(a,b,c) indicates a fused multiply-add a * b + c using binary32 values. The naive algorithm is via a … Read more
n % x == 0 Means that n can be divided by x. So… for instance, in your case: boolean isDivisibleBy20 = number % 20 == 0; Also, if you want to check whether a number is even or odd (whether it is divisible by 2 or not), you can use a bitwise operator: boolean … Read more