Question

Find the lowest common multiple (LCM) of 6, 10 and 14. *

2 points
A. 30
B. 140
C. 210
D. 280
​

Answer 1

Two options:

First option - list everything (waste time)

6, 10, and 14

6: 6, 12, 18, 24, 30, 36, 42, 48, 54, 60, 66, 72, 78, 84, 90, 96, 102, 108, 114, 120, 126, 132, 138, 144, 150, 156, 162, 168, 174, 180, 186, 192, 198, 204, 210

10: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210

14: 14, 28, 42, 56, 70, 84, 98, 112, 126, 140, 154, 168, 182, 196, 210

Second option - divide each option by the numbers to see if a whole number is the outcome.

30 / 6 = 5
30 / 10 = 3
30 / 14 = 2.14...

140 / 6 = 23.33...

210 / 6 = 35
210 / 10 = 21
210 / 14 = 15

Answer = C. 210

Answer 2

C. 210

Explanation:

Plugging it in directly

30/14=2.14 (not an integer)

140/6=23.33 (not an integer)

210/6=35

210/10=21

210/14=15

all of the above result in integers, so the answer is C.

D is not even checked because it is larger than 210