What is the largest decimal value you can represent, using an 86-bit signed integer?

2^85 - 1 or 38,685,626,227,668,133,590,597,631 Since you're using a 86-bit signed integer, the smallest number you can represent is - 2^85 and the largest number you can represent is 2^85 - 1. Now what is 2^85 - 1? 2^85 - 1 = 38,685,626,227,668,133,590,597,631 An easy way to estimate how large of a number you can represent is to take the common logarithm of 2 and multiply by (n-1) where n is the number of bits in the signed integer value. Doing that gives. 0.30103 * 85 = 25.587 which tells you that you can represent every integer up to 25 digits long and some of the smaller 26 digit numbers.