Medium
Find the odd one out.
Explanation
Explanation
Check which numbers are perfect squares: 25 = 5×5, 10,000 = 100×100, 100 = 10×10 — all perfect squares. But 1,000 is not a perfect square (there's no whole number that multiplies by itself to give 1,000). So 1,000 is the odd one out, option (4).
PRO TIP
Re-check your working by substituting the answer back into the original question.