Depth 1 · 28 s
Six party bags
12 biscuits and 18 sweets make at most 6 equal bags. The numbers that divide both are their common factors, and the greatest one is the most equal groups.
About this video
How many equal party bags can you make from 12 biscuits and 18 sweets, with nothing left over? This short animation lists the factors of 12 and the factors of 18 side by side. The numbers in both lists, 1, 2, 3 and 6, are the common factors: each of them divides both numbers exactly, so each is a number of bags that works. The biggest, 6, is the greatest common factor (some books call it the highest common factor), and it is the most bags you can make: six bags, each with 2 biscuits and 3 sweets.
The video ends with a shortcut for bigger numbers. Split each number into primes: 12 = 2 × 2 × 3 and 18 = 2 × 3 × 3. Both have one 2 and one 3. Multiplying what they share, 2 × 3, gives 6 straight away. The greatest common factor answers every question of the kind "how many equal groups at most?", from party bags to the biggest square tiles that cover a floor. This video goes with The Greatest Common Factor lesson of Number Theory Level 1 on Knaph.
This video shows depth 1 of Greatest common factor.
Learn Greatest common factorTranscript
- 0:00Twelve biscuits, eighteen sweets. How many equal bags?
- 0:04The number of bags must divide both numbers. Those are the common factors.
- 0:11The greatest is six. Six bags, two biscuits and three sweets in each.
- 0:17Or multiply the prime factors they share. Two times three.
- 0:23The greatest common factor, the most equal groups.