The significand is found by taking your number and moving the radix point until there is no fractional part, making it into an integer. In decimal this is making 1.45 into 145 by moving the point right 2 steps, and in binary this would be making 1101.0111 (13.4375) into 1101 0111 (215) by moving the point right 4 steps; in both cases these numbers aren't related to one another outside using the same digits in a similar ordering.