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BECE Mathematics 2015 Paper

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Question : 6

Total: 40

Express

120_5

as a number in base 10.

25
27
32
35

Solution:

Concept:

To convert a base‑5 numeral to base 10, multiply each digit by the corresponding power of 5 and add the results.

Explanation:

Write

120_5

in expanded form using powers of 5.

120_5 = 1 \times 5^2 + 2 \times 5^1 + 0 \times 5^0

Evaluate each term:

1 \times 25 = 25

2 \times 5 = 10

0 \times 1 = 0

Add them together:

25 + 10 + 0 = 35

Therefore,

120_5

equals

35

in base 10.

Answer:

35

(Option D)

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