159
Year review
Textbook: Part 4, lesson 148, pp. 70–71
GoalYear review: the number ray, expressions with letters, multiplying two-digit numbers.
New words
number ray · sonli nurpattern · qonuniyatexpression with letters · harfli ifodaprice · narx
Explanation
Numbers on a number ray follow a pattern: in 0, 10, 30, 60, 100 the added numbers are 10, 20, 30, 40 – the next is 50, so the next number is 150. Expression with letters: a shop sold a goods in a day and b are left – there were a + b at first. Trainers cost 2 times less than a tracksuit; if the tracksuit costs k som, the trainers cost k : 2.
Worked examples
34 × 7 = 30 × 7 + 4 × 7 = 210 + 28 = 238.
One ball costs f som, so 6 balls cost f × 6 som.
Class activity
“Pattern masters”: the teacher writes the first numbers on a ray (0, 10, 30…). Children find the differences, state the pattern and continue the ray by two numbers.
Practice
1
On a number ray: 0, 10, 30, 60, 100, … What is the next number?
150
2
42 × 5 = ?
210
3
34 × 7 = ?
238
4
7 × 45 = ?
315
5
Trainers cost 2 times less than a tracksuit. The tracksuit costs k som. Write an expression for the price of the trainers.
k : 2
6
Which is bigger: 30 × 100 or 30 + 100? (without calculating)
30 × 100