Look up printf format strings (possibly in C, the syntax is the same). More on reddit.com

Notice that there are three different ... decimal places), rounded to nearest, and round up. Usually, you want round to nearest. As several others have pointed out, due to the quirks of floating point representation, these rounded values may not be exactly the "obvious" decimal values, but they will be very very close. ... Capture the output of the "ring of commands" in a variable and use printf... More on unix.stackexchange.com

It is basically used to provide more configurability to your output. For example, if you want to print out this: Val 1 = 10 Val 2 = 1 Val 3 = 100 (Edit: the code format didn't seem to make the characters the same size, so I had to add extra spaces for alignment in reddit specifically) With the 10, 1, and 100 being from variables, how would you line them up? You could do complex logic that figures out the length of the number, then prints an appropriate number of spaces. Or you can just use printf and use the format string "Val %d = %5d". The %5d says "print an integer (d) that takes up at least five spaces (5)", so this means no matter how long the actual number is, it will pad extra spaces to make it take up at least five (though it it has more than five digits, then you meed to reevaluate the amount of padding you use). Similarly, you can also make the int appear in Hex, or have zeroes padded in front in spaces, have a floating point print with a certain number of decimal places (so 0.541 can be printed as 0.54 by using %.2f, with ".2" meaning "to two decimal places).n Edit: In use, my example might look something like this: System.out.printf("Val %d = %5d\n", i, vars[i]); More on reddit.com

I put together an example for you that prints the raw storage bits. I think it covers most cases and should print the stored value as close as possible. For 0.3 it prints 0.29999999999999998889776975374843450 value = 0.3 encoded1 = (5404319552844595 / 4503599627370496) * 2^-2 encoded2 = 1.199999999999999955591079014993738 * 2^-2 result = 0.29999999999999998889776975374843450 import java.math.BigDecimal; import java.math.MathContext; public class DoublePrinter { public static void main(String[] args) { // see https://en.wikipedia.org/wiki/Double-precision_floating-point_format // a double is stored as sign * significand * 2^(exp-1023) double value = 0.3; long bits = Double.doubleToLongBits(value); // the sign is stored in the upmost bit, same as long long sign = Long.signum(bits); // first bit long exponentBits = (bits & EXP_BIT_MASK) >>> 52; // next 11 bits long significandBits = bits & SIGNIF_BIT_MASK; // lowest 52 // add the implicit leading bit if not subnormal if (exponentBits != 0) { significandBits |= 0x10000000000000L; } // map to a more readable represenation (significand is stored as (value / 1L<<52)) long divisor = 1L << 52; int exponent = (int) (exponentBits - 1023); // compute result using BigDecimal var mc = MathContext.DECIMAL128; BigDecimal significand = new BigDecimal(significandBits).divide(new BigDecimal(divisor), mc); BigDecimal scale = new BigDecimal(2).pow(exponent, mc); BigDecimal result = new BigDecimal(sign).multiply(significand).multiply(scale); System.out.println("value = " + value); System.out.println(String.format("encoded1 = %s(%d / %d) * 2^%d", sign < 0 ? "-" : "", significandBits, divisor, exponent)); System.out.println(String.format("encoded2 = %s%s * 2^%d", sign < 0 ? "-" : "", significand.toString(), exponent)); System.out.println("result = " + result); } final static long SIGN_BIT_MASK = 0x8000000000000000L; final static long EXP_BIT_MASK = 0x7FF0000000000000L; final static long SIGNIF_BIT_MASK = 0x000FFFFFFFFFFFFFL; } More on reddit.com