Write each of the following numbers in usual form:

(i) $3.74 \times 10^{5}=\frac{374}{100} \times 10^{5}=\frac{374 \times 10^{5}}{10^{2}}=374 \times 10^{(5-2)}=374 \times 10^{3}=374000$

(ii) $6.912 \times 10^{8}=\frac{6912}{1000} \times 10^{8}=\frac{6912 \times 10^{8}}{10^{3}}=6912 \times 10^{(8-3)}=6912 \times 10^{5}=691200000$

(iii) $4.1253 \times 10^{7}=\frac{41253}{10000} \times 10^{7}=\frac{41253 \times 10^{7}}{10^{4}}=41253 \times 10^{(7-4)}=41253 \times 10^{3}=41253000$

(iv) $2.5 \times 10^{4}=\frac{25}{10} \times 10^{4}=\frac{25 \times 10^{4}}{10}=25 \times 10^{(4-1)}=25 \times 10^{3}=25000$

(v) $5.17 \times 10^{6}=\frac{517}{100} \times 10^{6}=\frac{517 \times 10^{6}}{10^{2}}=517 \times 10^{(6-2)}=517 \times 10^{4}=5170000$

(vi) $1.679 \times 10^{9}=\frac{1679}{1000} \times 10^{9}=\frac{1679 \times 10^{9}}{10^{3}}=1679 \times 10^{(9-3)}=1679 \times 10^{6}=1679000000$