WAEC 2025 · Paper 1 · Q1✱✱

Number bases

Find $(101_2)^2$ , expressing the answer in base 2.

Worked solution (try it first)

Change to base ten: $101_2 = 4 + 1 = 5$ .
Square it: $5^2 = 25$ .
Change back: $25 = 16 + 8 + 1$ , so the answer is $11001_2$ , option D.

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