Question

Give the following numberin Base 10.1215 = [ ? ]10

Answer 1

To convert a number in base five to base ten, we shall use the expanded notation with the place value of each of the base five numbers.

The procedure is shown below;

$\begin{gathered} 121_5 \\ \text{Assign place values starting from the right to the left} \\ \text{That is 0, 1 and 2.} \\ We\text{ now have}; \\ (1\times5^2)+(2\times5^1)+(1\times5^0) \end{gathered}$

We can now simplify this as follows;

$\begin{gathered} (1\times25)+(2\times5)+(1\times1) \\ =25+10+1 \\ =36 \end{gathered}$

ANSWER:

$121_5=36_{10}$