What you are actually practicing
Reversing digits is not just reading a number backwards. Every digit moves to a different place, so a 3 that meant three hundred may end up meaning three, and a 1 that meant one now means a thousand.
The task is small but it exercises place value directly — the same idea behind expanded form and behind rounding.
How the game works
You are shown a number with a reversal arrow, and four candidates. Pick the reversed number. A wrong pick reveals it immediately.
Easy uses three digits with no trailing zero. Medium and hard use four digits, including the cases where a zero moves to the front.
The relationships worth knowing
Reverse one digit at a time, right to left: 3,482 → 2, 8, 4, 3 → 2,843.
A zero that moves to the front disappears: 1,200 → 0021 → 21.
Reversal is its own inverse: reversing twice gives the original number back.
Strategies that actually raise your score
Read the digits right to left, write left to right. Starting at the units digit and writing outwards is faster and less error-prone than trying to hold the whole number in mind.
Check the first digit of your answer against the last of the question. 3,482 must produce a number starting with 2. If your answer starts with 3, you did not reverse anything.
Do not assume the length is preserved. A trailing zero drops off, so 1,200 reverses to a two-digit answer. Options with the original length are deliberate traps.
Use the digit count as a filter. For a four-digit number with no zeros, the answer is also four digits — anything shorter is out before you finish reversing.