Actually, I lay that at the school's feet. They say they care. They should not have left you behind.I just wanted to point out, the issue is not quite so simple as you guys are thinking.
For some it may be ability to conceptualize abstracts, for others it can be remembering the procedures (if they were ever taught them).
Not every teacher or method taught is the same either.
When I was in 4th grade, we had just gotten to multiplication, barely even started, when I broke my arm very badly. Needed a few procedures and missed weeks of school. When I got back to class they had all been introduced to the concepts and my teacher told me to catch up by just sending more homework home. As if my father had the time to teach me or my mom was ever good at math herself. The class had 35 other students and the teacher didn't have the time to help me. I had a lot of trouble writing without my dominant hand, after months of bad grades the school finally loaned me a device for typing that was more like a keyboard with a tiny screen than a computer. I don't know what to call it, lol.
Point is, I got really behind, really discouraged, and gave up on understanding math. The class kept moving forward and that was that.
I got caught up in other subjects due to my love of reading.
How many other kids fall by the wayside would be hard for even statisticians to answer.