Write each of the following decimals into expanded form :

243.689

We have:

243.689 = 200 + 40 + 3 + 0.6 + 0.08 + 0.009 [Separating according to place values]

$= (2 \times 100) + (4 \times 10) + (3 \times 1) + \Big(6 \times \dfrac{1}{10}\Big) + \Big(8 \times \dfrac{1}{100}\Big) + \Big(9 \times \dfrac{1}{1000}\Big) \\[1em] = 200 + 40 + 3 + \dfrac{6}{10} + \dfrac{8}{100} + \dfrac{9}{1000}$

∴ The expanded form of 243.689 is $\Big(200 + 40 + 3 + \dfrac{6}{10} + \dfrac{8}{100} + \dfrac{9}{1000}\Big)$