Which of the following  pre-computer age of 19th century is use for addition and subtraction*1 pointpascal's calculatorside ruleabacusprjector

The correct answer is "Pascal's calculator". This device, invented by Blaise Pascal in the 17th century, was used for addition and subtraction. Here are the steps to arrive at this answer:

1. Understand the question: The question is asking which of the given options was used for addition and subtraction in the pre-computer age of the 19th century.

2. Evaluate the options:

   • Pascal's calculator: This is a mechanical calculator invented by Blaise Pascal in the early 17th century. It could add and subtract two numbers directly and could perform multiplication and division through repeated addition or subtraction.

   • Slide rule: This is a mechanical analog computer. The slide rule is used primarily for multiplication and division, and also for functions such as roots, logarithms and trigonometry, but is not normally used for addition or subtraction.

   • Abacus