Theory:

Decimal point position:
1. When a decimal number is multiplied by \(10\), \(100\), \(1000\), \(10000\), we move the decimal point by \(1\), \(2\), \(3\) and \(4\) places respectively to the right side of the number.
 
2. When a decimal number is divided by \(10\), \(100\), \(1000\), \(10000\), we move the decimal point \(1\), \(2\), \(3\) and \(4\) places respectively to the left side of the number.
Example:
1. Multiply \(125.643\) by \(10\).
 
Number of zeroes in \(10\) is \(1\). So, move the decimal point by one place to the right.
 
\(125.643 \times 10 = 1256.43\)
 
 
2. Multiply \(125.643\) by \(100\).
 
Number of zeroes in \(100\) is \(2\). So, move the decimal point by two places to the right.
 
\(125.643 \times 100 = 12564.3\)
 
 
3. Divide \(125.643\) by \(10\).
 
Number of zeroes in \(10\) is \(1\). So, move the decimal point by one place to the left.
 
125.64310 \(= 12.5643\)
 
 
4. Divide \(125.643\) by \(1000\).
 
Number of zeroes in \(1000\) is \(3\). So, move the decimal point by three places to the left.
 
125.6431000 \(= 0.125643\)