You can learn how to add and minus, multiply and divide. You can learn the process to figure these out. You can learn how to look at a maths problem and find the answer.
These things don't mean anything if you can't figure out how to create the maths problem in the first place.
Life isn't going to go around handing us maths problems to figure out. We are not going to be given maths questions to answer. We need to know how to create the maths for ourselves. We need to know how to figure out how much our shopping will cost us. Sometimes we need to know how long something will take to finish. But we can't figure these things out if we don't know what to add to what, or what to multiply by what.
Having a calculator doesn't help you either.