Each measure is its own little recipe. Do them one at a time and they never get muddled.
Mean — Add Then Share
Add every value up, then divide by how many there are. For 4, 8, 6, 2: the sum is 4 + 8 + 6 + 2 = 20, there are 4 values, so 20 ÷ 4 = 5. The mean is 5. It's literally sharing the total out equally — as if everyone got the same.
Median — Order, Then Pick the Middle
Put them in order first, then take the one in the middle. For 8, 2, 6, 2, 9, order them to 2, 2, 6, 8, 9 — the middle one is 6. (What happens when there's an even number of values is the big trap on the next rung.)
Mode — the Most Common
Find the value that appears most often. In 2, 2, 6, 8, 9 the number 2 shows up twice and everything else once, so the mode is 2. Ordering the list first makes the repeats easy to spot.
Range — Biggest Minus Smallest
Take the largest value and subtract the smallest. For 2, 2, 6, 8, 9: 9 − 2 = 7. The range is 7. That's it — one subtraction.
The Habit That Saves You
Whatever you've been asked for, write the list out in order first. It hands you the median, makes the mode obvious, puts the biggest and smallest at the two ends for the range, and doesn't change the mean. One tidy move, three measures easier.