23
Multiplying and dividing by 10, 100 and 1,000
Textbook: Part 1, lesson 23, pp. 72–74
GoalLearn to multiply and divide numbers by 10, 100 and 1 000; calculate with money.
New words
banknote · banknotmultiplication · ko‘paytirishdivision · bo‘lishsom (currency) · so‘m
Explanation
When we multiply by 10, 100 or 1 000 we add as many zeros to the end of the number as the factor has. When we divide by 10, 100 or 1 000 we strike out as many zeros from the end of the dividend as the divisor has. Money: banknotes of 100 000, 50 000, 10 000, 5 000 and 1 000 so‘m.
Worked examples
4 × 10 = 40; 6 × 100 = 600; 8 × 1 000 = 8 000; 70 000 : 1 000 = 70.
27 notes of 100 000 so‘m and 13 notes of 10 000 so‘m: 27 × 100 000 + 13 × 10 000 = 2 700 000 + 130 000 = 2 830 000 so‘m.
Class activity
“Shop game”: a mini-shop is set up with paper banknotes. Seller and buyer work out a price (for example 347 000 so‘m) and calculate the change.
Practice
1
38 × 100 = ?
3800
2
76 × 1 000 = ?
76000
3
250 000 : 100 = ?
2500
4
x × 10 000 = 670 000. Find x.
67
5
A buyer gave 3 notes of 100 000 so‘m and 6 notes of 10 000 so‘m. The price is 347 000 so‘m. How much change is due?
13000