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WAEC Data Processing 2021 Paper

Question : 3

Total: 40

2

in denary is

Solution:

Concept:

Binary numbers use base 2. Convert to denary by multiplying each digit by its place value, which is a power of 2, and adding the results.

Explanation:

The binary number is

101100101_2

. It has 9 digits, so the leftmost place value is

2^8

Write the place values from right to left:

2^0, 2^1, 2^2, 2^3, 2^4, 2^5, 2^6, 2^7, 2^8

Now multiply each binary digit by its place value:

1 \times 2^8 = 256

0 \times 2^7 = 0

1 \times 2^6 = 64

1 \times 2^5 = 32

0 \times 2^4 = 0

0 \times 2^3 = 0

1 \times 2^2 = 4

0 \times 2^1 = 0

1 \times 2^0 = 1

Add these values:

256 + 64 + 32 + 4 + 1 = 357

Answer:

C. 357

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