It's all a matter of significant figures.
He is using the rule that if the numbers being multiplied and divided have 3 significant figures, the answer should have 3 significant figures (-1.10 kJ).
But in this case, the answer starts with 1.
I prefer to use the rule that if the answer starts with 1, but none of the operands does, you keep an extra significant figure. That would make the answer -1104 kJ.
It all depends on what rules you follow for significant figures.