The lengths of three rods are 6 cm, 9cm, and 11 cm. How can you see those rods to measure a length of 14 cm?
Take the two rods of 9 cm and 11 cm and stack them up end to end. That will make 20 cm. Then, place the 6 cm rod beside one of them. The distance from the end of the 6 cm rod to the end of the two stacked up rods is the desired 14 cm.
(9 + 11) - 6 = 14
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