Activity › Discussion › Math › LOWEST COMMON FACTOR GRADE 6 › Reply To: LOWEST COMMON FACTOR GRADE 6

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Solution 1
Step 1: Given – The first Bell rings every 15 minutes and the second Bell rings every 20 minutes.
To find – At what time will both Bell will ring together
Concept – so basically here we have to find LCM of 15 and 20 and that will be the time both Bell will ring together.
Step 2 :
List the prime factors of each:
15:5 x 3
20:2 X 2 X 5
Step 3: Multiply each factor the maximum number of times it occurs in any of the numbers.
The occurrence of Numbers in the above example:
5 – one time
3 – one time
2 – two time
So 5 X 3 X 2 X 2 = 60
This gives us 60, the lowest number that can be divided evenly by 15 and 20.
Hence the bell will ring together after 60 minutes.
Solution 2:
Step 1:
We are given two numbers 6 and 8
To find: LCM of two numbers 6 and 8
Step 2:
List the prime factors of each:
6:2X3
8:2X2X2
Step 3: Multiply each factor the maximum number of times it occurs in any of the numbers.
The occurrence of Numbers in the above example:
2: three times
3: one time
So LCM of 6 and 8 will be 2X2X2X3= 24
Solution 3:
Step 1:
We are given three numbers 9,12and 15
To find: LCM of three numbers 12,9 and 15
Step 2:
List the prime factors of each:
9: 3X3
12:2X2X3
15:3X5
Step 3: Multiply each factor the maximum number of times it occurs in any of the numbers.
The occurrence of Numbers in the above example:
3 two times
2: two times
5: one times
So LCM will be 3X3X2X2X5=180