What the AMC 8 Tests
Arithmetic and fractions/decimals/percents; ratios, rates, and unit conversion; basic number theory (divisibility, primes, LCM/GCD, remainders, digit problems); counting (lists, complements, simple casework, permutations of small sets); probability of simple events; averages and simple statistics (mean, median, mode, range); geometry (perimeter, area, angle sums, triangles, circles, coordinate basics, Pythagorean triples); patterns and sequences; logic puzzles and reading carefully. Twenty-five questions, forty minutes, no calculators.
Gap Fillers
Distance rate time; average speed is TOTAL distance over TOTAL time, never the average of speeds ( km at km/h and at km/h averages ). Work problems add RATES: pipes filling in and hours together fill per hour.
Mean = total count (so "the mean of numbers is , remove one, mean becomes " means the removed number is ). Median is the middle of the sorted list; mode the most frequent; range max minus min. Adding a constant shifts mean/median; multiplying scales them.
The minute hand moves per minute, the hour hand per minute (and per hour). At : minute at , hour at , angle . Days of the week cycle mod ; leap years add a day.