1. Rule of sign solving is known as VBODMAS:
- V stands for "Vinculum" or "Bar"
 - B stands for "Bracket" (order as small,medium,big)
 - O stands for "Of"
 - D stands for "Divisibility"
 - M stands for "multiplication"
 - A stands for "Addition"
 - S stands for "Subtraction".
 
2. Multiplication of signs:
1. Multiplication of two plus gives again a plus.
2. Multipication of two minus gives a plus.
3. Multiplication of one plus and one minus gives a minus.
 
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