JAMB Mathematics 2018 Paper

Concept:Addition in base eight uses place values of powers of 8, so whenever a digit sum reaches 8, we carry 1 to the next column.Explanation:Add the units digits: $4_{\text{eight}} + 7_{\text{eight}} = 11_{\text{ten}}$.Since $11_{\text{ten}}$ is greater than the base 8, divide: $11 = 1 \times 8 + 3$.Write the remainder $3$ in the units place and carry $1$ to the eights place.Now add the eights digits with the carry: $5 + 6 + 1 = 12_{\text{ten}}$.Again, $12 = 1 \times 8 + 4$, so write $4$ and carry $1$ to the next place.There is nothing left to add, so the final carried $1$ becomes the leading digit.Thus, the result is $143_{\text{eight}}$.Answer:$143_{\text{eight}}$The correct option is D.