10th grade Honors Math Student does not know basic math

I have a 15 yr old 10th grade HONORS student that cannot do basic Math. She currently maintains an A average in her Algebra II Honors and Geometry Honors courses. We have recently begun asking simple questions, what is 10% of $250, if you aretraveling at 60 mph, how far can you travel in 1 hour, etc etc. She has no idea how to begin an answer.

Although she has been an honors student throughout her education and maintained an A (sometimes B) average, she does poorly onstandardized testing, 50 percentile or below. We now feel like we understand why, she does not truly understand math concepts, even the most basic math. We suspect she is taught mostly "cheats" and "short cuts" and repeats patterns to solve problems and with theuse of a calculator no longer has a need to know basic multiplication.

My question is, how do we begin at-home remediation? Is there a source that could help organize our journey from basic math to where she currently learning? Our only efforts are printing practice sheets of elementary percentage, fraction, multiplicationworksheets. This has proven difficult in finding enough info in one place and in tracking progress. Tackling this is extremely overwhelming and I am hoping for a real guide to how to do this correctly. Thank you for any information you can provide.