Think about how math works. You don't have time to sit there and calculate stuff out all the way so act fast. Often you can get the answer just paying attention to the low-end digits for example if it's multiplication and one of the numbers multiplied by has a 0 in the lowest digit position, and only one of the answers has a 0 there, you know that's the answer.
Or if it's a modulus % question and you divide a positive number by a positive number, you know the remainder can't possibly be negative, so if two of the three are negative that gives your answer.
Or just do some simple add/subtract on the first couple digits or so and probably will be able to eliminate the bad answers quickly without even calculating out the full number.
Everyone should have at least IQ level Ladybug. Come on people! It's not that hard to at least get that much.