12
Divisors and multiples
Textbook: Part 1, lesson 12, pp. 37–39
GoalUnderstand divisors and multiples; find the divisors and multiples of a number.
New words
divisor · bo‘luvchimultiple · karralidivides exactly · butunlay bo‘linadieven number · juft son
Explanation
If a divides by b with no remainder, then a is a multiple of b and b is a divisor of a. For example, 84 : 12 = 7, so 84 is a multiple of 12 and 12 is a divisor of 84. The number 1 is a divisor of every number. A divisor of a number is never larger than the number, but it has endless multiples, found by multiplying the number by 1, 2, 3, …
Worked examples
The divisors of 20 are 1, 2, 4, 5, 10, 20 (six of them).
The multiples of 6 are 6, 12, 18, 24, 30, …
Class activity
“Divisor pairs”: children write 24 as a product of two factors (1 × 24, 2 × 12, …) and so find all its divisors.
Practice
1
How many divisors does 18 have?
6
2
From 14, 24, 30, 45, 54, 70, 72, 100 write the multiples of 6.
24, 30, 54, 72
3
Is 7 a divisor of 343?
Yes, 343 : 7 = 49
4
Write the first five multiples of 9.
9, 18, 27, 36, 45