Yes, that title is misspelled for those of you in the know . . . but it is so spelled because that is the way 99% of people search for it. No judgment here.
No harm done. If you are curious, the appropriate spelling is Data Sufficiency.
So what exactly is a Data Sufficency question? Unlike the problem solving questions, DS questions are not concerned with your ability to actually solve the question. They are testing to see that you understand when you have enough information to do so.
This is actually a very important skill.
Think about this, for Fiscal Year Now you have to determine if your department will invest in a new product development idea or if you will spend your budget on donuts and diet coke – I’m kidding, but only kind of…. (I’ve done consulting work for some strange companies)
What do you need to know to determine which choice you will make?
You’ll need information about the product development costs, projections for sales, the break-even point, how much capital (human and financial) you could conceivably dedicate and you’ll need to know the cost of providing (or not providing) the donuts and diet coke.
Having that information does not answer the question of whether to invest in a new product or keep your staff stuffed. But you can make that decision because you have all of that information.
That is data sufficiency on the gmat.
In contrast, problem solving is like reviewing last year’s budget. You either hit your numbers or you did not. It’s all there and already done.