A data processing apparatus and method of operating a data processing apparatus are disclosed. Comparisons are made between first and second floating-point operands received. A more significant portion of the first floating-point operand and of the second floating-point operand are subject to comparison. The more significant portion of the first floating-point operand minus a least significant bit in the more significant portion is subject to comparison with the more significant portion of the second floating-point operand. A less significant portion of the first floating-point operand and of the second floating-point operand are also subject to comparison. In dependence on the outcome of these comparisons, right-shift circuitry is used selectively to perform a 1-bit right shift on a difference calculated between the first floating-point operand and the second floating-point operand.