Once. I freaked out because I saw a cop driving behind me and I was afraid I might get pulled over for blocking traffic by driving next to another car while in the left lane so I sped up to 50 in a 45 zone to pass it and then the speed limit changed to 35 and I forgot to slow down.
Zero, though I was lucky - I regularly drove passengers around when I was on my restricted license (meaning I should only be driving myself or people with a full license for two years or more).
Two. Because the first time was because I was driving a little too fast, and then second time was because I forgot to change my front sticker (in the US, you have to change it annually > )