Find the lowest common multiple of 24, 36 and 40.
Correct answer: C. 360
- A. 120
- B. 240
- C. 360
- D. 480
Explanation
Prime factors are 24 = 2^3 x 3, 36 = 2^2 x 3^2 and 40 = 2^3 x 5. The L.C.M. takes the greatest power of each prime: 2^3 x 3^2 x 5 = 8 x 9 x 5 = 360. A common mistake is 120, which is the L.C.M. of only some of the factors and does not include the required power of 3.
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