Shop math quiz.

Author:Rose, Steve
Position:Shop talk

Many of the machine tools used in our industry are called CNC machines. What does CNC mean? Computer Numeric Control.

Which of these words is the most important?



Numbers control almost every aspect of machining. The print is described with numeric tolerances, the programs are combinations of numbers, machines operate at feed rates and speeds, which are all numbers.

So, to succeed in the machining industry it is important to understand numbers. Working with numbers means mathematics. To keep you on your toes, here is a short quiz to test your mathematics skills.

Check the RTSI web site at for the results.

Pass it around to your co-workers, have fun and good luck!

1) What is the decimal equivalent of 27/40?

2) A 1/4-20 external thread is required on a 1.5" length. How many threads will be formed on this length?

3) You get a new box of 10 inserts. If you used 4/5 of them, how many are left?

4) A boring bar has a 7:1 length-to-diameter ratio. If the diameter is 1.250", what is the length?

5) If a triangle has two angles of 30 each, what is the size of the third angle?

6) A right triangle has one side length of 3.25" and another side length of 4.55", what is the length of the hypotenuse?

7) Find the length of the diagonal (line JK) of this cube, which has an edge length of 4.5cm.

8) One machinist has worked at the XYZ Co. three times as long as a newcomer. An old-timer has worked there five times as long as the newcomer. The...

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