BECE Mathematics 2017 Paper

Change the decimals to the form whole number $\times 10^{a}$Where the power (a) is the number of times you have to move the decimal point in order to get a whole number When you move to the right, the power is negative and when you move to the left, the power is positive $64.5=645 \times 10^{-1}$ (The decimal point has to be moved once (1) to the right)$0.015=15 \times 10^{-3}$ (The decimal point has to be moved three (3) times to the right)From the law of indices $\frac{a^m}{a^n}=a^{m-n}$ $=43 \times 10^{-1-(-3)}=43 \times 10^{-1+3}=43 \times 10^{2}$Now change the result to standard form. The standard form rule says the decimal point must be after the first non-zero digit.$43=43.0$ so we have to move to the left once and since to the left, the power is positive (1)$43=4.3 \times 10^{1}$From law of indices, $a^m \times a^n=a^{m+n}$$43 \times 10^{2}=4.3 \times 10^{1} \times 10^{2}=4.3 \times 10^{1+2}=4.3 \times 10^{3}$ in standard form