BECE Mathematics 2013 Paper

She goes to school and back everyday. She covers the distance twice (to school and back home) every day.Total distance covered each day $=2 \times 2345 \text{ m}=4690 \text{ m}$Calculations Kilo means 1000 , hence divide the meters by 1000 to obtain the kilometers.$4690 \text{ m} = \frac{4,690 \text{ m}}{1000} = 4.69 \text{ km}$Calculations$1000 = 10 \times 10 \times 10 = 10^3$$4690 \text{ m} = \frac{4690 \text{ m}}{1000} = \frac{4690 \text{ m}}{10^3} = 4690 \times 10^{-3}$Note: From law of indices $a^{-b} = \frac{1}{a^b}$$\frac{1}{10^3} = 10^{-3}$Change the whole number $\times 10^{-n}$ form to decimal by moving the decimal point by the value of the power to the left.$4690 = 4690.0$ (Every whole number has .0 which isn't written)$4 . \overset{\text{⏜}}{6}\;\; \overset{\text{⏜}}{9}\;\; \overset{\text{⏜}}{0} .0 \times 10^{-3} = 4.69 \text{ km}$In summary, any time you are dividing by $\text{1 n 0 s}$, you move the decimal point of the number you are dividing $n$ times to the left.Where $\text{n 0 s}$ means number of zeros after $1$In the above example 1000 has three (3) zeros hence we have to move the decimal point of 4690.0 three times to the left.