If , find the value of x.

By what number should (-6)^-1 be multiplied so that the product becomes 9^-1?

By what number should be divided so that the quotient may be?

Write each of the following numbers in standard form:

(i) 57.36

(ii) 3500000

(iii) 273000

(iv) 168000000

(v) 4630000000000

(vi) 345 x10⁵

Write each of the following numbers in usual form:

(i) 3.74 × 10⁵

(ii) 6.912 × 10⁸

(iii) 4.1253 × 10⁷

(iv) 2.5 × 10⁴

(v) 5.17 × 10⁸

(vi) 1.679 × 10⁹