For digits before decimals point, multiply each digit with the positive powers of ten where power is equal to the position of digit counted from left

Decimals
For digits before decimals point, multiply each digit with the positive powers of ten where power is equal to the position of digit counted from left to right starting from 0.
For digits after decimals point, multiply each digit with the negative powers of ten where power is equal to the position of digit counted from right to left starting from 1.
1) $$10^{0}=1$$
2) $$10^{1}=10$$
3) $$10^{2}=100$$
4) $$10^{3}=1000$$
5) $$10^{4}=10000$$
And so on...
6) $$10^{-1}=0.1$$
7) $$10^{-2}=0.01$$
8) $$10^{-3}=0.001$$
9) $$10^{-4}=0.0001$$

2021-05-20
1) $$\overleftarrow{720432}=2(10^{0})+3(10^{1})+4(10^{2})+0(10^{3})+2(10^{4})+7(10^{5})$$
2) $$\overleftarrow{1923000}=3(10^{3})+2(10^{4})+9(10^{5})+1(10^{6})$$
3) $$\overleftarrow{12678200}=2(10^{2})+8(10^{3})+7(10^{4})+6(10^{5})+2(10^{6})+1(10^{7})$$
4) $$\overrightarrow{0.0024623}=2(10^{-3})+4(10^{-4})+6(10^{-5})+2(10^{-6})+3(10^{-7})$$
5) $$\overrightarrow{0.0000056}=5(10^{-6})+6(10^{-7})$$
6) $$\overrightarrow{0.0000878}=8(10^{-5})+7(10^{-6})+8(10^{-7})$$
Note : Anything multiplied by 0 will be 0.