WEBVTT

1
00:00:00.000 --> 00:00:05.282
Here is the problem: Find the greatest common factor of 90, 150.

2
00:00:05.732 --> 00:00:11.235
Find the greatest common factor (also called GCD or HCF) of the numbers.

3
00:00:12.035 --> 00:00:14.043
Prime factorization of each number.

4
00:00:14.494 --> 00:00:29.018
Euclidean algorithm for GCF(90, 150). 150 equals 1 times 90 plus 60; 90 equals 1 times 60 plus 30; 60 equals 2 times 30 plus 0.

5
00:00:29.468 --> 00:00:32.533
The last non-zero remainder is the GCF.

6
00:00:32.983 --> 00:00:39.612
Confirm with shared prime factors. Multiply the primes common to every number, each with its smallest exponent.

7
00:00:40.412 --> 00:00:42.072
So the answer is 30.

8
00:00:42.522 --> 00:00:46.400
30 is the largest whole number that divides every number exactly.

9
00:00:47.200 --> 00:00:49.673
90 divided by 30 equals 3.

10
00:00:50.123 --> 00:00:53.420
150 divided by 30 equals 5.